where do you earn/buy your steam keys

I often use Gamesplanet, has often some nice deals. Sometimes GamersGate and Gamebillet.
And for bundles mainly HB and Fanatical. Rarely use IG or GMG.

GamesPlanet
WinGameStore
GameBillet

These regularly add a bit of extra to the discount, so at least for someone from the EU they tend to be the cheapest option.

Then there's also
GamersGate (which used to be owned by Paradox until Valve got upset about that and forced them to spin it off into its own company)
2game
eTail.market
JoyBuggy
Voidu
DLGamer
AllYouPlay

Though generally I tend to just use isthereanydeal.com to see where I can find the cheapest (official) sellers of any given game

Twitch - HitSquadGodfather

Discord gaming channels

Alienware Arena

Fanatical is the only page I use for keys.
The rest of the games I bought, I purchased them on Steam.

Instant Gaming

CDKeys,sometimes Eneba ,but mostly on Fanatical,Humble,GMG or steam
And lately HitSquadGodFather

Since Steam introduced automatic refunds that actually work, I rarely buy a key from a key shop. I would rather pay a bit more with the option of getting 100% of my money back than pay less and be stuck with a game I played for only 50 minutes.

Guy in the Tesco parking lot, or behind the bowling alley on Tuesdays - for personalized deals.

I trust isthereanydeal.com, aside from the sites in your OP I've bought a couple of games from WinGamesStore.

Steam
Fanatical
Humble Bundle
Gamersgate
WinGameStore
GreenManGaming
Indiegala
Gamesplanet - if they have good offers, which isn't that often.

Green Man Gaming has been growing on me. Bought the odd bundle from them back in the day. When they stopped doing those, I stopped shopping there, but I decided to check it out again a few years ago, and was surprised to see some good discounts on newer games. It's also way better than Fanatical & HB when it comes to getting keys for giveaways, since you can easily & quickly view region-lock information.

Steam Store, because CrossCode, RIVE and Rabi-Ribi aren't available anywhere else in Steam-redeemable forms for giveaways. :P

(And occasionally Fanatical or Green Man Gaming for a copy of DOOM or a bundle or something... Also usually check GamersGate but their regional pricing usually sucks compared to the other two... And Humble Bundle... exists.)

Exclusively Fanatical and HB. Those two work fine and have good deals, so no point in fucking around with other sites.

wherever gg.deals says whatever game i'm looking for is the cheapest. i've bought from pretty much all of them listed above.

More than exclusive stores I rather take a look once in a while at these 3 websites:

• SteamDB tracks Steam game prices and sales history. You can see historical lows to target games that might be good for giveaways.
• IsThereAnyDeal is another price tracker that also shows deals from authorized retailers like Fanatical or Humble Bundle you might have missed.
• GG Deals is similar, allowing you to track wishlist games and see price drops across various stores.

Fanatical like in 99% of time

Hmm, odd not seeing Kinguin here on the list. I've had positive experience with them so far

ZakaZaka. Pretty reliable store, and I can get games that I can't in Steam.

The only one I know about that hasn't been mentioned so far is Opium Pulses.

Also Lootboy for me before there death (removed all way to get free diamonds by daily connexion / code / watching ads)

I wouldn't bother. Someone will say you are gaming the system and remove all the cv from your giveaways. Unless you just don't care about the cv and want to just give away a lot of keys.

Fanatical for bundled ones, Games planet to buy unbundled for giveaway, Steam store for myself

Mostly Fanatical these days since HB turned lame imo.

I used to use IndieGala a lot when it was new, but lately, it's been nothing but cheap porn games and other stuff I'll never care about.

I used to use GMG a lot, but lately, it's been failing me, so I've been using GMG less and less. One thing I used to like about GMG is their keys weren't region-locked.

Nowadays, I mostly rely on Fanatical and Humble since they're more reliable. However, I also like GOG and am wondering why we can't specify non-Steam game keys on here. Think about it, why isn't there a metagifts or a goggifts? I know it's rarer, but why not try to support as many platforms as possible? Oh well, I can give those keys away directly on my social platforms instead.