What are you using for backgas? Buying something for a deco reg that minimises the parts you need should something go wrong is not a bad idea.
Generally, most regs will work fine. I've used Scubapro mk20 with r395 second stages for a while, but I've also used HOG regs, DiveRite, Apek etc.
Personally, I much prefer regs with turret first stages - the rotation of the turret allows you to stow the hose neatly and get the hose routed comfortably when in use. I've found non-turret first stages tend to produce a feeling that the hose is too short and is being pulled out of your mouth.