I agree with Feep, Dragon Nest has a better combat system than TERA. More actionny, more options which makes the player more involved. I'd rate Vindictus even higher than Dragon Nest though.
Vindictus action combat feels pretty much spot on for me, it's really similar to Monster Hunter or Demon's/Dark Souls system. High risk/reward system, you can't spam your attacks/skills at all because of the short stamina bar. Keeps the player on his toes all the time. If you get hit even once against bosses, you're in for troubles. Not to mention the physics engine is pretty good (think it's actually Valve's Source engine), lot of destructibility and items/rubbles you can use at your advantage.
I got two characters to level 22 during TERA sneak peek event (berserker and sorcerer) and whilst the game is really impressive graphically, I felt pretty disconnected with the action itself. BAMs and the Secret Base dungeon were fun enough but it wasn't as intense as I expected, it feels a bit "artificial" with hotkeys pressing, I hoped we would get more freedom with the control of our characters.
I'll play a few more CBTs, see if the game gets more challenging but it felt pretty grindy/repetitive up to level 22 so far.