Okay:
Ammochain: with it's requirements and without the trait you'll blow up any enemy pn sight with chainfire, but sooner or later(rather sooner) you'll run out of bullets. So this trait is VERY usefull if you know how to use it.
Cateye:also with requirements is rather usefull. You're lurking on the level, knowing that if you see enemy, he doesn't see you. And you can blow him up before he knows what have hit him.
Army of the Dead:designed for double shotgun rather, where armor is a HUGE problem. There even if close up into close quaters, 6 times armor is applied( if I'm correct).
Vampyre:Gives 3 HP which is 6% without Iro, 5% with Iro1, 4,3% with Iro2 and 3,75% with Iro3. It just gives a little boost to HP, useful for crowds.And it's some kind reference to my idea.
Blademaster:Junk without dodgemaster, with it lets you destroy enemy group without letting them hit you.(Junk with Butcher's Cleaver);
Fireangel:My favourite master trait, lets you blow up every enemy with your RL in melee, fly away with Rocket Jump, blow up barrels just like mines, dodge missles of any enemy without thinking of walls, and if that wasn't enough, you're walking with 120 HP( if you're good player).
There isn't the best, it just depends of your play style.