I'm not really sure which ones are best. I think they would be the dice, the bulldozer, and maybe the block and the laser. I think the destruction items have an edge over mobility items. I tried to offset that by making several of them less handy in a pinch (startup for laser and bomb). I kind of just spitballed the cooldown times based on my gut.
My favorites are the bulldozer and laser because they were fun to make, between the particles and the speedy movement.
(Yeah, left is score and right is time)