Minions of Mirth - Good game, multiplatform. The community used to be kick arse, but it's kinda died since the chat rules turned more kiddy and after a while it does get boring.
Imbalances on the three factions need to be sorted out direly. PVP wise a mellee character is useless. The monsters have been uppeed which is really nice. The tri class system makes for some incredibly overpowered characters, it seems like a brilliant idea but in the end it adds to the imbalance - everyone can wear heavy armour, everyone can cast spells, everyone can hit like a tank. It's just how you specialise in the end. You can play as a wide veriety of the NPC templates there, but class wise it can be quite restrictive so far. I think they might fix that though. One time payment of £15, good.
Overall it will have you hooked for a decent amount of time, but in the end you won't play it as much.
Shadowbane - This is the game I play most of all. It's completely player driven, you can buld cities, take over other cities, have huge wars, etc. It's PVP based, the leveling system i short and sweet, you won't be stuck on a grind for a thousand days. You can get to top level in about a month of average playing. Well balanced classes, good fighting system, the graphics are dull seeing as the game is old. At times the lag canbe crippling - but mainly it's just to do with CN (the Asian zerg that ruins servers, which is currently having it's collecive arse kicked on Thurin). The game is free with all expansions - except you'll have to go to the forums to find the download link, which is irritating granted. The download is LARGE, so prepare to wait a while.