I have a Komos for CO2 and a Taprite for Nitro. The Komos "looks" nicer to me, but honestly, they both seem to perform equally well.
Features I would recommend:
1. Two pressure gauges. Tank pressure and serving pressure. I do wish the lower pressure gauges were 0-50 psi instead of 0-100 psi. Beer serving pressures for me tend to be maxed out at about 15 psi. The 100 psi gauge makes it a little difficult to be too precise.
2. An outlet shutoff valve. The Komos didn't come with one. Can't imagine why not.
3. A check valve to prevent beer from backflowing into the regulator.