I've tried many games , i remember tibia , very good when it appeared , Mu ,.The next generation Brought games like Ryl 1( very nice pk , but now no exist more this game ) , silk road ( its fun but no a lot ) , and ko ( the best pk system of all games ) , tantra ( this game had a system much like ko pk ) , Later coming Lineage ( very good game but pk is boring ) , All this game was free . Guild wars you need pay for start to play , for this i no mention it or age of camelot AOC , and others . Wow Start new age of mmorpg , now have a lot options . I try for fun others like rohan ( like lineage ) , rappelz ( dont like ) , metin2 ( suck ) ,last chaos ( no comment ) the classic anarchy online , eve etc.
But anyone its better than ko in pk system . I think the option is maybe try private server of tantra ( i remember one in spanish imperioonline ) This game have 3 religions and have 2 zones of pk you can fight vs the others 2 religions , have jobs like ko , archers , warriors , magicians , etc . The pk is very nice , and you get points when you kill enemy . The graphic no is the best ,Its like ko =) , but the game is fun . I cant say you any server on now but if you go google i sure can get one =) .
I dont mention games like archlord , 9 dragons , ragnarok ( suckkk) , cabal etc .Cuz this games suck .
I dont play aion , and final fantaxy , i cant give my opinion.