Ive tried Caldwells and Cutting Edge. Cant say ive tried both with peppers but both work. Make the brine and give it a sugar source to munch on to speed things up a little more. I normally just use a tbs or two of kraut juice when i want a starter.
My criteria had less to do with the pepper and more to do with risk and fridge space. My fermenter pale is rather large but ive never gotten mold using it. Cayenne probably is better with a longer ferment. I got a few bottles of Crystals so im in no hurry.
I got bonnets out the wazoo and my pale is full atm. A 2 quart jar with air lock though is just a bit of a pain in the fridge. Once its sour enough i can chop it down finer. Im fairly certain it will fit in a quart jar. It will still ferment in the fridge just slower. I can use it when its convenient to do so. Chance of spoiling will be pretty low.