MapleStory? Honestly? Well I guess everyone has their opinions. As for the question, Guild wars is a one time payment but their pvp isn't as good as it could be. I don't know any free mmo's that much though. If you have $20.00 laying around get guild wars.
Well. i presonally love Rohan the pvp was good BUT the BEST FREE MMO i played was 4Story , they have events every month where you can get about 30$ free cash shop and the pvp is amazing( its good for raids) every day they have wars where both fractions are put into 2 maps its epic and town seige isnt out yet.. once it is.. its going to be Awesome!!
Ok a MMORPG is a Massive Multiplayer Online Role Playing Game. A MMO is a Massive Media Onlinegame. So please try to capitalize it all next time. This is what your title said MMOrpg. Now here is the correct grammar for it MMORPG. Thanks.
Now I would like to tell you Runescape but that is only satisfying for the first couple of months to a year so no don't play it.
Ultima Online; it has good PvM and great PvP (depending on the server) and lets you pretty much customize your entire experience in the game. While they do have pay servers they have an abundance of free servers; some of which are clone servers of the pay ones, and some that have a ton of custom items. The client can be downloaded for free here: http://download.cnet.com/Ultima-Online-Mondain-s-Legacy-client/3000-7540_4-10432237.html And here is a list of downloads to help you connect to the free shards: http://www.uodemise.com/downloads/
However if you wish to play the free shards I advice against running the UO program after you've installed it, run it through Razor or ConnectUO.