... until you feel like you need 2 HP ports, or a swivel turret, or a bottom LP port....
To the OP: From what I've learned around here, it seems the 2nd stage regulator is what really makes the most difference in how easy a reg breathes (assuming you have a basic, decent quality 1st stage). The local people I talk to all seem to agree that the ScubaPro G260 is the nicest-breathing 2nd stage reg you can buy right now. I haven't tried one, so I can't say myself. My shop carries every brand I can think of except Deep6, HOG, or Poseidon. They carry ScubaPro, AquaLung, Apeks, Dive Rite, Hollis, Oceanic, Aeris, Atomic, SubGear, and probably something I'm not thinking of. The shop owners and other staff all seem to have the G260 on their personal reg sets.