First choice for a beginner in a 4X genre (GA inside)

Master of Orion 1

Alpha Centauri is probably one of the better choices to start with as it actually has something of a story (which should hopefully help pull you in a little bit more than MoO did), and the interface isnt too much to deal with (though the shortcuts can be confusing initially).
Even though Stellaris is listed at the top on votes, I cant really say it counts as a 4x in my eyes, its also not that great unless you want to pick up a bunch of dlc for it.
If you choose to go with a MoO game, go with #2 as thats generally the favourite, but also has an ease of use the other two original MoOs dont.

Edit:
Additionally, if you like Alpha Centauri, it will open a window for you onto the Civilization series - the 4th of which has some decent scifi mods

space engineers

Only played 5 games on the list but I would go with Alpha Centauri.

However, it is not really a space 4x strategy since it takes place in a single planet.

Even if "Science fiction 4X" games sounds pretty narrow, there's a lot of different games in this category, and it is definitely going to come down to your personal taste.

The Stellaris you listed in the poll is a very good game, highly praised, and i voted for that one.

However two other suggestions i'd like to make, that aren't on your list, are:

Sword of the Stars. (NOT SotS II. 2 was very very buggy and bad.).
A turnbased game, with several unique races, each having their own specific playstyle, in a race to expand, colonize and either crush or coexist with your neighbors. The combat is done between turns, in real-time segments of up to 10 minutes before a draw is declared, and the combat continues at the next turn shift. The game allows you huge customizability in how you design your ships, and has an enormous tech tree, that is random rolled to a certain degree each game, so it will never quite be the same.

Sins of a Solar Empire.
A realtime game, focused more on sustainability, exploring and keeping your economy flowing, while sending your army around to defend and attack as needed. This game relies more on you having a few strong capital ships, rather than a swarm of ships, which both makes for more polarizing combat, but perhaps also a bit simpler.

Both games do significantly better with a group of friends to play with, rather than a solo sitting, but keep in mind that a single game can take a full day.

I am not that much into Strategy either, so the few games of this genre I enjoyed had strong stories (or atmosphere) to go with them... Like:

1. Myth (The Fallen Lords) -- might be a bit too old to recommend;
2. Starcraft -- ditto;
3. Darwinia -- not exactly 4x...
4. Homeworld.

Ok, so maybe I should have said Homeworld, only. :D

Cheers!

Master of Orion 2 is still the best space 4X ever made. There’s a reason every space 4X is still compared to
It. (There are threads on reddit, steam, paradox, etc. asking if X game is as good as MoO2) It’s the gold standard. The new master of Orion feels like a watered down remake. Endless space (1 and 2) are variations on a theme, but they’re basically just prettier versions of Master Of Orion 2 with more story Stellaris is as well, but fuses some of Paradox’s Grand strategy mechanics into it. It’s not quite as good. Basically, they’re more of the same - but no better. Galactic civilizations, same answer.
Beyond Earth is civilization v in space. That’s it. Easily the weakest of the bunch

Master of Orion 1 is great if you want a rather simpler game - it has deep strategy, but only a few things going on. Less mechanics make it easier to easy into, but it definitely feels like you’re stepping back in time to a previous era. Still one of the best games around, especially if you don’t mind old games / graphics / UI

somehow I never played alpha Centauri. I’ve always heard great things about it, but can’t comment

https://videogamegeek.com/thread/617837/master-orion-more-master-games
http://scientificgamer.com/in-praise-of-master-of-orion-2/
https://www.gamespot.com/articles/the-greatest-games-of-all-time-master-of-orion/1100-6132108/

(me looking at your voting options.)

never played
never played
never played
STELLARIS YES

If you're into retro-gaming, you could try to find Ascendency. I didn't try Master of Orion 1 nor 2016 but I really liked Master of Orion 2.

Master of Orion (2016) - Well you already played it and liked it. A pretty good choice then to keep playing. And it certainly isn't "hardcore", so a good choice for beginners.
Master of Orion 1 - Interesting game but no.
Master of Orion 2 - Always a great option, though the UI is outdated.
Master of Orion 3 - Forget that this one exists.
Sid Meier's Civilization: Beyond Earth - meh
Sid Meier's Alpha Centauri - Same as MoO2
Endless Space 1 - Similar too MoO 2016
Endless Space 2 - Good choice if you liked either MoO 2016 or ES1
Stellaris - My favorite, but you should only consider with a lot more experience
Endless Legend - Good game, but nothing breathtaking. Offers little challenge for the experienced 4X gamer.
Galactic Civilizations 1 - never played it
Galactic Civilizations 2 - It was a good one that kept the genre alive, at a time when 4X offered nothing in space anymore. Worth trying but wouldn't be my first choice.

One game you are missing is Distant Worlds: Universe. It's Master of Orion 2 in real time. on a far larger scale. Winning hasn't much to do with strategy though, it's more about tactics. You can automatize many features to your preferences, it might still be too much for a beginner though.

So summed up I suggest:
Keep playing MoO 2016
Endless Space 2 if you want more after you mastered MoO.
Stellaris if you mastered ES2.

Endless Space 1 is a pretty darn good entry into the genre, Stellaris is a good option too but has a strong dependency on DLCs to provide a full experience sadly.
Try Endless Space, is awesome.

Games like Distant Worlds: Universe, and other more niche space4X tend to be hardcore in their mechanics so maybe not the best entry point.

Civ 5 and 4 are easy to get into compared to many other x4. for example Europa is a little more complex. One thing I should point out about x4. They are often among the worse DLC abusers, Paradox for example are rage inducing and often immoral when it comes to the number of DLC you require for their games. So if you're trying to aquire some x4 game unless you are 100% sure you want to play it for a while and are willing to dish out some cash, I would completely avoid buying it unless it is in a bundle. Paying 100$+ for a single game is not unusual if you are buying full price.

Beyond earth is meh, I would go with a civ game over beyond. The Endless games are mostly all good, Stellaris is great. Master of Orion is only recommended if you are more experienced with x4 and are less likely to be turned off by outdated and unfriendly IU. I would go for a newer game where you only need to battle the AI/other players rather than the AI AND the UI. You can go back to those later on if you find the time in the future and really love x4 /are interested in the history of such games.

so my suggestion: Civ 5 or Endless series. I do not recommend Civ 6 until more content is released, in general being the first guinea pigs testing out new games is not ideal for x4 games - a bit like new OS lol.

sry I only know 3X games.

Get it? XXX?

While Stellaris is the best game on the list, it's also real time-strategy albeit with a pause button. Endless Space 2/Civ V( would not recommend Beyond Earth) on the other hand, are turn-based, so it might be easier to take your time fiddling around. All 4x games have a learning curve though so it might be less time consuming to just skip to Stellaris and play that for a few rounds, learning as you go.

why isn't Galactic Civ 3 on the list?

just to add to the list, also:

• space empires 4 & 5 (with balance mods) UI is oldish, and default AI lacking for experienced 4X gamers, but for a beginner could be a good entry point (but as you already played MoO 2016... not sure you still qualify for beginner ^_^ )
• distant worlds: universe, a good one (but wouldn't recommend it for a beginner)
• pandora: first contact ( Beyond Earth clone)
• Star Ruler 1 & 2
• Sword of the Stars 1

I've been playing Alpha Centauri since it first came out, still have the original PC game disc and box. I still go back to play it every couple of months, it is my favorite science fiction 4x game. You can get it on Gog.

I voted other. If by strategy you also include strategy turn based RPG then I suggest Disgaea. If not then.. I don't have anything to suggest. XD I heard good things about Civ series.

I'll just say that while Endless Space 1 has a lot of cool stuff going for it, it is NOT newbie friendly. The UI isn't great and neither are the tutorials/in-game guides.
Maybe the sequel does things better - can't say because I've not played that yet.

I wish I could help you out, but I'm a newbie to 4X, myself, having started my first one—Fallen Enchantress—earlier this year. I won it here on SG, and I've enjoyed what I've played of it so far. I've got a few other 4X games in my library, including ones on your poll, but I haven't gotten to them yet.

Civilization III was one of the first 4x I've played I still have the CD for it.

sorry, I haven't played any of the poll listed games

bump

4X? This is not exactly X4 type, but space-sim, but very enjoyable :)

X2 / X3 Albion Prelude / X3 Terran Conflict / X4 Reunion (bleah - they're f**d X-series with X4)
Example: https://www.reddit.com/r/X4Foundations/comments/749zfa/die_hard_x3_fan_x_rebirth_and_x4_hype/

I propose you X3 Terran Conflict + mods. A great game, very playable :)
https://store.steampowered.com/app/2820/X3_Terran_Conflict/

Several years ago I was trying out GalCiv 2, but quickly got very bored with it.
This year I tried ES1, and got really hooked and intrigued with the genre. Thinking of buying Stellaris, GC3 and ES2 when there is a good discount for their "GOTY" versions.

Homeworld is best strategic game