If you want to buy new, I'd also suggest the Azodin reg. Ran one on my Kaos for a while then moved it to my Phantom. It is a good reg, great for the price if you are buying new. It just does not like CO2. Only issue I had with mine was when I loaned the Kaos to a friend and they dumped it full of liquid CO2. Saw couple of them in the BST this week for $20 a piece
If you want to go cheaper the WGP regs are a good call. Just get the "ergo" or Black Magic if you can. They can be adjusted without having to depressurize first.