A collar for sure. It really helps me to get in the right headspace when I have my collar on.

I'm going to cheat and pick two First, rope; there's just nothing as versatile as a few dozen feet of hemp rope. Second, the Hitachi Magic Wand, because I'm a sucker for forced orgasms.

A riding crop.

Honestly, nothing. I prefer being restrained by a strong partner and restraining them with my legs, I'd rather use hands for impact/pain play with spanking or hitting, I've never used collars, and I'm excited by things like blindfolding but I really don't need it to be happy.

I really prefer more raw materials anyway, like being gagged with a bandana rather than a gag. So really, I don't need anything!