i've tried rakion, gunz, rumble fighter, space cowboys and i was wondering if they're are any pvp based mmo that requires skill and not grind

Of those you listed, only Rakion is a MMORPG.  Planetside is a MMORPG based PVP game, but since it isn't free like all those games you did list  I doubt you will want it.

 Guild Wars, no grind, nice pvp, takes some skill.

Guild Wars is the best option for seriuos pvp, it´s hard to play but also really good.  Complex strategies, lots of skills and lots of hours. Best pvp game.

If you are looking for a realm vs realm game you could try Regnum or Warhammer Online if you don´t care about the fees.

Guild wars is ok if your into the instanced dungeon thing, that game would have perfect if it had open world pvp, but it dosnt and what passes for pvp in that game gets to be routine after while.

I will admit that I havnt played it since the days of the rambo builds and invinci-monks but I just dont see how that much could have changed considering the the games pvp content is limmited to the arena.

to the OP:  I see that you played SCO, alot of us SCO vets are playing Ace Online. Thats the north american version of that game, if you liked SCO visit  http://ace.subagames.com/guide12.aspx

if you decide to play I know that FUB brig. BCU on the prelude server, is looking for new members, they are a small brigade consisting of just a few members but are ranked 5th on the server. They use teamspeak, actively war, and go the extra mile for helping thier members get geared up.

if SCO wasnt your thing you might want to take a look at a couple of the other games that suba has now but i doubt if they are anything other then the typical korean grind monster money pits

 considering the the games pvp content is limmited to the arena.

Lol, Guild Wars pvp isn´t limited to the arena,the arena is the first place but you have to unlock the other places, afther that you will unlock team arenas and finally Heroe´s Ascent,the hardest one, teams formed by 8 people in a lot of different game modes fighting to reach Heroes´ Hall,so don´t say is limited.

And you also have Guild vs Guild (ver important) , Alliance battles, 1 vs 1 (with heroes)  and event pvp battles.

Never say Pvp in GW is bad or limited.

P.D.: It is very easy to unlock the other places, all what you have to do is win 5 times,so i sopouse that i you thought it was only the arena maybe you didn´t win,and if you talk about invencible monks maybe you were using wrong skills or you were fighting against him alone,teamplay my friend.

If you want skill based PvP that requires some teamwork, try Infantry Online.

Skill based PvP that requires running and gunning for the most part, Combat Arms.

I'm been playing Guildwars for the past 3 years and 3 months, and this game is very in-depth. It's easy to learn, hard to master. I'm a current player in a Top 100 guild for Guild vs Guild battles, and I am Rank 9 in Heroes Ascent. I can tell you, that this game is very fun, and it has changed ALOT since the game has come out, for the better or worse, I can't really say, as I enjoyed back then and now.

Guildwars is entirely based on individual skill, as well as team play..

If you want a good player-skill-based PvP game I would recommend either Vendetta Online or Planetside.