There's nothing like the first time they say.
And losing your mmorpg virginity in any of them will be exciting. But, as stated above, once you see how it plays from day to day, month to month, year to year, every mmorpg afterwards will not give you that initial feeling back ever again.
I put nearly five years into Everquest. The first couple of years were a blast, in fact it was a blast until they released Lucilin and Planes of Knowledge. They began making everything easier for newcomers and really took away the challenge for the old timers.
I didn't even purchase 3 of the last 4 expansions. Legacy of Yakesha, Gates of Doom, and Omens of War. Did get Lost Dungeons of Norrath, it was pretty good.
You definitely will enjoy your first experiences though, the "unknown" is the greatest part about most things, including games. And from the readings; WOW seems to have done it correctly by removing the feel of a grind and you can level up quickly if you want to or casually stroll through the game either in groups, duo, guilds, pvp/pve or solo. There is no pressure to group or join a guild like most other mmorpgs, that to me is what makes WOW greater than them all.
You might want to try out Anarchy Online, for now it is FREE to play till 2006 and you can't beat FREE when it comes to a MMORPG. Anarchy Online is a Sci/fi game with WWII weapons lol. Well it has a few laser weapons, but, I found for the most part the weapons to be WWIIish. I played an Engineer so I could design pet robots. And with the unique implant system of enhancement discs, one could create a robot 20 levels higher than themselves, possibly higher, but, that was as far as I got.
Enjoy either, when they are NEW, most often you will. ;)