Action-Arcade MMO
Most mmos in the late 90s to the early-mid 00s are just rehashed of the point-and-click formula. Potions don't have cooldown, Pvp and PvE are entirely dependent level and gears. Even with the implementation of Guild/Nation Wars where composition of a team plays a part, it does not offer an engaging gameplay with sufficient depth for the players.
The first arcade-action MMO I'd play was Lunia. It's a korean game. Up till today, the pvp aspect this game had once offered still best many current ones I had tried, although to be fair, I'm fairly out of touch. Zoning, Sidestep, Shifiting, Half-Dash, Skill-Cancelling, Combo-ing with precision and timing, Wake-up mind games, First hits etc. are some of the heaviest focuses of their Pvp aspect. It's a game where Spammers find it hard to break into the top bracket of players. The best Pvper for NA server was Xpecial, who move on to TeamSoloMid in League of Legend.
Unfortunately, like every game which became popular, it was heavily casualised for the mainstream audience.
http://www.youtube.com/watch?v=7195ZmVIImU&feature=relmfu
And yes, the Koreans are extremely good players.