Just before all of this I was playing Oblivion ( and have been since mid 2008 ) I loved it and had made 3 complete playthroughs with different characters. One of which I still have. I loved Oblivion. It was the only game I would play. My favorite original character, an Assassin Khajiit who I had named H'Skar. I've loged over 800 hours onto this one single character and have great fun every minute of it. Then, I remember hearing about Skyrim's release. I was estatic.
But now I have Skyrim, have already logged about a 100 hours into it since release and while Skyrim is great in it's own right, with wayyyy better graphics I can't help but miss Cyrodiil. I've thought about it for about a week now, wanting to boot it up again, just to be in the role of my ole Khaiit. Hell, I loved that character so much I even continued him in a way in Skyrim. I made another Khajiit, assassin-like build who is a descendant of H'Skar. A Khajiit, great with stealth and archery, I have rightfully named his J'Skar.
I guess what I'm trying to say is: now that Skyrim is out, I'm turning into an "Oblivion Guy" , just like all those other turned into those "Morrowind Guys".
TL;DR: Oblivion is my game. I don't think anything will ever top it IMO.