I put my vote with FALLOUT3...
I absolutely adore the original FALLOUT games, I have all 3 of them and FALLOUT3...
and
I adore the Eldar Scrolls series, Morrowind was amazing, and I personally think it's better than Oblivion, but Oblivion is still a bloody good romp. My only problem with it was, after playing through the full GOTY edition of Morrowind, Oblivion GOTY was just too much more of the same. Granted much shinier and prettier and all, but still just more of the same, and I just prefered Morrowind.
I really liked the first 2 FALLOUT games, I thought FALLOUT:Brootherhood of Steel was a bit crappy, not the best of the 3 originals, and again, to be honest, I liked the first FALLOUT the most. That is until FALLOUT3!!!
I liked the gameplay of FALLOUT 1 and 2, BoS wasn't bad, similare, but not the same, but I love the whole FPS feeling that Bethesda manage to give to psuedo-medi-evil fantasy, that with it being transfared to the more familier grounds of FPS, ie Sci/fi themed, it was just a match made in heaven. PURE GENIUS!!!
and of course: Bloody Mess + V.A.T.S. = pants on head retarded fun!!!