I already have a 200 Bucc, but I also find enjoyment in playing my Mech/Dual Blade/Phantom a lot as well. I'm also in the midst of leveling a Mercedes in my spare time. Now the thing is, in terms of pure game and class mechanics, which one would be overall best for smashing bosses and shredding mobs up? I'll put a poll up. The reason I ask is that I want to make the best use out of my mesos and possibly NX, since I don't want to be class hopping in finding that one bossing class.
From what I read, Phantom is probably the best due to sheer versatility. However, I know Mechanics are getting buffed soon, and Phantoms are getting nerfed soon. Mechanics will get about +40% more damage (passive + Overtune), 30% PDR ignore, 10% more HP (more survivability), Double Dice, and summons will last even longer. Phantoms will lose some duration to their stolen buffs, there will be a cooldown implemented in skill swapping, and other nerfs here and there.
Dual Blade and Mercedes I know are strong, but from what I read they both don't do so well at Empress. However, I still enjoy their fast and furious playstyle. I'm sure however, that with max avoid all other bosses in the game won't be able to touch either classes.
Buccs I already know they aren't exactly the best boss killers, since they're far better at mob killing. However he's still the highest level person I got.