Really, just get both. They play somewhat differently and each person prefers one slightly over the other - they'll keep you entertained for many, MANY hours, and offer excellent replayability. If you pick just one, you'll probably regret it later. :P

Get FO3 first. If you like it, play FONV (which is, in my humble opinion, slightly better).

Get FO3.

Much bigger Modbase,better gameplay and in my humble opinion perfect apocalyptic feeling ...

There are even some Mods which change the game completly just like the Nehrim mod fpr TESIV Oblivion...

Use search FFS -.-

Personally i want to get both of them,
But i would go for F NV Ultimate now, 75% is as good as it is going to get,
and wait with F3 GOTY, hoping it will also have 75% until the end of the sale, then it will be really cheap (unless you're australian or something).

As far as gameplay goes, F3 is more like the older fallout series, F NV feels kind of big and empty in between towns.
but both of them have a great modding community that fixed most problems, and you shouldn't play without mods anyway.

I actually did things backwards - my bf bought me New Vegas and I LOVED it... Put 100+ hours in with all the DLC (make sure you play Old World Blues, some of the best DLC I have played in any game. Freaking hilarious). And now, having enjoyed New Vegas so much, I've just bought FO3. So while I can't say which one is better, I had an awesome time with New Vegas so will recommend it to anyone :)

can someone mention the price of fallout 3 and fallout NV, and collection if their is any. i cant find it in steam store.

I liked NV much more than FO3

Fallout3 :)

New Vegas, by far. F3 has a few good parts, but overall it's greatly inferior to NV.

New Vegas

I just got New Vegas Ultimate Edition and you should too, sir.

Aha, finally can get my Fallout 3 GOTY copy :D

Both for 15€ now!

Fallout 3 all the way

All of the above. Only $15. DEFINITELY worth it.

Preferably fallout 3 here, I just did not like new vegas that much.

New Vegas

New Vegas. It was developed by a different team with more serious attitude to the fallout universe. This feels much more like 'fallout' than fallout 3.