I personally like World of Warcraft myself.
I have been playing online games for many years, and I believe that WoW is very well built. WoW caters to its players by providing a solid system for questing, leveling, exploring, grouping with other players, and more.
Even now, WoW constantly updates to bring more utilities to its players such as built-in voice chat, a sleek UI, and an application specifically for players to find other players for groups.
Blizzard, the makers of WoW, also care (and act) to stop cheaters and gold spammers. This is a BIG deal to me since I have left mmorpgs in the past because of rampant cheaters that no longer made the games fun.
WoW also has a huge community, so you are pretty much guaranteed to meet someone you can talk to. Sure, there are the general online jerks, but the real world has jerks too. I have met many people online that I chat with every chance I get.
Many people complain about WoW, but I still believe that it is the best mmorpg out there mainly due to the attention that is put into the game and its players by Blizzard.