I would disagree that anyone who's played Vanguard would find WoW boring.
I love Vanguard, but all of the rampant bugs lately have forced me to look elsewhere until they get them fixed. I bought both EQ2 and WoW to fill the void, and EQ2 didn't make the cut. Runs horrible on my system for such an old game. It's also a slight bit too "cutesy" for my taste with all of the fairies, frogmen, mushroom patches and everything else. Not a total turnoff, but less appealing to a guy my age than either Vanguard or WoW.
WoW, on the other hand, runs perfect and plays as smooth as you could hope for. It's more of a beginner MMO which fits me better since I just started on them a month ago. And I don't find it boring at all so far. The art and atmosphere is completely different from Vanguard, so it feels like an entirely different game. It's more fast-paced than Vanguard is, and mobs aren't nearly as much of a pain in the ass to kill. Overall, it just seems to be a smoother experience. And most importantly.. NO BUGS. No bugs when you're trying to group with people, no bugs when you're trying to bind equipment, no bugs that crash you to the desktop in the middle of a large group quest, no item bugs.. no bugs of any kind so far. And though I know eventually that I'll run into one, it sure is a nice change from Vanguard.
The downside to WoW is that the audience is a lot younger and more immature.. no matter what someone may tell you. I've only been playing it for 4 days now, and already I've ran into two very unique characters. One was a kid that logged in as a female character under the name "buttsex" and shouted over the chat "who wants to *@(! me in the *@@ for 5 dollar??" over and over for about 5 minutes until he was banned. I never saw that kinda stuff on Vanguard after even hundreds of hours of play. You also get a lot more people talking like: "y r u afk.. lol dont u kno we r tryin 2 group???" which gets under my skin for some reason.
They each have their positives. Vanguard looks a hell of a lot better, is a deeper, more wide-open and much larger game, has a mature audience, but is filled with so many bugs it'll have you pulling your hair out in no time. WoW is a much younger audience but has gameplay much smoother than Vanguard, runs much better, and is for the most part bug-free.
I think for the beginner, WoW is a better choice. I started out with Vanguard, and it was like being thrown into the Lion's Den. If I wasn't such a stubborn, dedicated person then I may have given up after my 164 deaths the first two weeks I played it.