Yeah I'm into these.
I was eying a game named ArchLord in EB Games today. It kinda looked interesting and I checked out some videos of it, decent. They recently made it f2p so that's a plus.
WoW has been in consideration for a long time.. but I'm afraid of getting addicted.
WoW is for newbs.
Archlord is a huge grindfest focused on PVP, which apparently isn't even that great.
Vanguard is difficult to get into and more difficult to play, but probably more rewarding the end.
If you're newer to MMOs go WoW or something, but be prepared as it gets pretty shallow endgame.
If you don't want to spend any money there are a few OK games you can play for free on http://www.e-games.com.my/games.asp
Knight Online is probably the most similar to any of the ones you mentioned. Granted it's not as good, but it is free to play.
Anarchy Online isn't bad for being free. Of course, I have very little experience with MMORPGs, having ONLY played AO, and a little bit of Project Entropia (btw you can make money for FREE in this one, if you're worried about wasting money).
I'm thinking about going ahead and buying WoW. In general I've heard it's a pretty fun game. I was originally hesitant on getting addicted and the monthly fee, because I just didn't want to pay it.
I've played a lot of MMO's in my past... a LOT of Runescape off and on.. is lvl 96 85 mining and fletching means anything to you... you'll know how much I played. xD I also played a lot of Guild Wars. Lvl 20 W/Mo IDS Farmer fo life.