Ok, so, first things first: I don't think Fallout 3 is a bad game, it's a fine game. I have heard many people, however, say that fallout 3 was BETTER than new vegas, and I literally can't think of a reason why anyone would prefer 3 to new vegas, besides these 3:
1. WAH WAH BUGS UNOPTIMIZED WAH
This is one, but i can only see it if you haven't played new vegas since like the 2nd week it came out. The patches largely fixed most of the problems that could be fixed (Bethesda's engine is garbage, obviously) So yeah if you guys stopped playing it because of bugs and prefer fallout 3 to it... IT'S FIXED.
2. Nostalgia! or REVERSE NOSTALGIA OH NO
Obviously Fallout 3 was something new at the time (As I have mentioned before, Fallout 1 and 2 were not the same types of games) and the concept was cool that people did everything in there (even though a lot of the quests were stinkers) and you got bored of the concept by the time new vegas rolled around. If you're this person, well, I'm not going to be able to say anything to convince you, but let it be known that you guys missed a far superior game.
3. OBSIDIAN SUCKS/I HATE GOOD WRITING/WAH IM A BIG CRYING BABY IN THIS ANALOGY
ok so I could only think of 2, so please tell me, unless you think the writing in F3 is better then in that case... nah, just kidding. I hope people don't think that :/