All of the traps are bad in their own special way.
I hate PP-Zero traps because they are so common in the later dungeons. >.<
I hate Pitfall Traps because you lose new recruits/have to go through another floor
(but I'm pretty sure that if you're in a dungeon that has "B" floors you go up a floor.
I hate Explosion traps because they kill your clients on a mission. Also, after I step on it,
no matter how much I try to maneuver myself so my partner doesn't step on it, he does anyway. >.>
I hate Sticky traps because they always seem to destroy the item you need most. (For me, reviver seeds.)
So yeah, most of the traps are bad.