Their lobe catalog is extensive. They also offer basically everything else: lifters, springs, retainers, tools, you name it.
I use Bullet cams quite a bit, but Comp gets most of my business. They are fairly close to me (next state down) and if I order a custom grind cam on Monday, I will have it by the end of the week. Hard to do that with other companies.
I've tried the smaller named cam designers before and I've been bitten...
You tend to use the company that you've had a good history with. I will continue to use them until they jack me up in some way or another...hahaha