I have now played both Fallout 3 and New Vegas. I like both games, but there are some features/mechanics in each that I like better then the other game.

1) I like 3's more simplistic ammo use. Switching ammo gets too "involved" for my tastes, though I know others love this aspect.

2) I like New Vegas' addition of campfires and ingredients.

3) I like New Vegas' addition of weapon mods.

4) I like 3's continuation after finishing the MQ.

There are other bits and pieces that I'd like to see in my "Perfect Fallout" game. What are some of yours?

PS: I find 3 is overall a little more to my liking then New Vegas

When Broken Steel altered the ending and allowed playing after it, the whole thing was ruined. The ending lost its entire purpose. It was great that New Vegas had definitive ending.

Pretty much this.

And better writing, better quest design, and better, more involved, more well rounded comapnions with their own stories and personalities.

Oh, and one more thing. Real choices with real consequences for not just our actions, but also our inaction.

Pretty much this as well.

Also, it's not like you're forced to use the different types of ammo. Hell, for my entire first playthrough I didn't touch any of the special ammo types not once.

For the most part, I prefer New Vegas over FO3 in almost every aspect.

I really disliked New Vegas's definitive ending, and the little effort that seemed to be put into the envrionment. Fallout 3 had a leg up on that.

The rest though? New Vegas does it just as good. The questing is just as good, the shooting is much better by the simple edition of iron sights, and I love all of the crafting I can do. I would say that New Vegas is a wonderful Fallout 3.5 in and of itself, a expansion-packy sequel that doesnt change things nearly as much as a usual Bethesda sequel, but offers a more refined experience to tide us over until Fallout 4.