Loved Fallout 3, I found it better than New Vegas simply for the reason that it was all new to me, so It could just as good to only play New Vegas.
If you own the PC versions of Fallout 3 and New Vegas there's a mod that connects the maps
So you can have all the same game mechanics from New Vegas on fallout 3 and freely move between. From what I last remembered all the quests worked (bar the main story line) and NPC spawns worked as well when in D.C.