I played both Oblivion and Skyrim. Oblivion was fine. I really liked its spellcasting system - you could exploit it to stack effects that would result in devastating spells.
I was sad they took that feature away in Skyrim.
Skyrim had also great atmosphere... almost, though not quite, on par with Morrowind. But I hated its interface.
I play on PC, and seeing the interface tailored for consoles, making it a clunky, ugly, cumbersome thing for a PC user annoyed me to no end. But it was still great!
I'm curious about ESO, but I don't play MMORPGs. They're such a huge time sink!