F3 more action NV more roleplay.
Decide yourself.

new vegas is more polished

USE THE SEARCH FUNCTION AND BUY NEW VEGAS.

I say both.
I have heard a lot of people say that once they played the system of New Vegas, they didn't want to go back to 3. However, I really like 3... so, maybe start with 3. And for the next sale, get New Vegas.

you may have some problems with FO3 if you use win7

non of them

New Vegas. Both is better, but start with the first. But if just one, get Vegas.

You may have framerate problems if you run fallout 3 on a quad core

Play both like 80 hours each one... Still prefer New Vegas.

I had the same question and went for 3 cos you get all the DLC as well. As to the problems with Win 7, I've had none in about 5 hours. There was a problem with the processor having 4 virtual cores - caused FO3 to crash every 5 minutes or so, but a small config change fixes that. Config fix here if you go with 3

Both.

Fallout 3. It's just a better story and the way it is told is better than New Vegas .

If u have Win7 Fallout 3 not work on this platform, treatment exist but in not working on steam versions. so i prefer New Vegas becoz it have more stability(without mods of course)

i got both. but that was a while back :P

New Vegas is better

It's easy, GET BOTH!

Fallout 3- Better story and better radio

Fallout NV- Better gameplay(ironsights), story and radio aren't as good

Fallout 3. It's the GOTY version and is the same price as New Vegas without all it's DLC, therefore it has more content than New Vegas but for the same price. Not only that, but in my opinion it's better anyway.

New Vegas. It has by far better storytelling.

I would advise you to get both if you can. As far as i never played New Vegas i can't say for sure which game is better. And i don't like to compare best RPG's. They are all good. Dragon Age - Fallout - Mass Effect - Neverwinter Nights - Gothic - The Elder Scrolls - etc. Can you say for sure which is the best? Wouldn't be sure. They are all good in their own way.

I asked the same question here, and I ended up buying New Vegas. It has way more missions and story than Fallout 3, so I recommend NV

If you get NV, make sure you get the Ultimate Edition for $2,50 more.

Both? :)

New Vegas is better than FO3 in almost every aspect. The only thing FO3 does better is probably the atmosphere.

For everything else, from the story to the characters and gameplay, F:NV is a step above.

Both, because there's a mod that allows you to play New Vegas with BOTH maps, allowing you to be the Vault Dweller while wandering the New Mojave, and also perform quests in the Capital Wasteland.