Kardwill: I was really excited when Obli was released, but it was really a letdown for me. The landscapes were pretty but generic, the map markers and instant movement killed the incentive to actually find your way in the country (and thus I never felt "home" there like I did in Vvadenfell, or in other games like Gothic 2), the UI felt clunky, most NPCs looked stupid, the quests too linear, the imperial capital was meh, the dialog system... Only stuff that I thought were an improvement were the map and the log.
Oblivion was the first game in the series that I played, I loved the way the terrain subtly changed as I adventured. After playing Skyrim I just couldn't get back to oblivion. Skyrim is both easier to mod and nicer looking; the faces in oblivion are truly horrifying even by the standards of the time.
I have yet to play Morrowind, but I am looking forward to playing daggerfall. The large generated map and random dungeons intrigue me.