Ultima Online was my first and still favorite MMORPG back in the late 1990s/early 2000s but when I tried EverQuest for the first, the 3D world and depth of races/characters/NPCs blew me away.
Then I tried Dark Age of Camelot. The 1-world-but-3-continents/factions concept amazed me. There was always 'the others' and a sense of citizenship with the group of players I could actually interact with. Everyone in UO/EQ was a potential rival/friend. In DAOC I knew where my loyalty lied and the enemy was always clear.
Then I played Ragnarok Online -- my first Korean MMORPG. Again, blown away for totally different reasons. The music, the colors, the sprites, and GIRLS!! Lots of girls played Ragnarok. I didn't meet any girls on UO/EQ/DAOC -- 95% boys, 5% house wives.
Next up was Star Wars Galaxies. No more 'levels', back to skills ala Ultima Online but in a totally different and more complicated way! 3D persistent housing! Crafting! Dancing at the local cantina as a totally legit profession! Multiple PLANETS!! OMG!
Then came World of Warcraft -- nothing I hadn't seen before this time. But it was presented in the most streamlined manner and was the first MAINSTREAM MMORPG. Everyone my age was playing. I felt like the grizzled veteran of the genre/ I knew the mechanics. I taught my friends how to tank. How to heal. How to lead a raid, etc. Again, amazing for totally different reasons.
Sad to say, I haven't felt anything new since WoW. But I honestly don't think its because the genre is played out. Its just we haven't been shown anything different. That might change this year with plenty of promising games in the pipeline -- Shards Online, Albion Online, Camelot Unchained, etc.
If you still think the genre has hope, check out my ~1yr old website, http://mmos.com I hope to see you on my next adventure.