Re: power supplys and multiple rails
In my opinion, neither is definitely better than the other. Most PSUs are single rail anyway, with multi-rail PSUs just splitting up the single rail. The PSUs that truly have more than one +12v rail are typically very high wattage PSUs, as well as those for servers.
As long as you have a quality PSU to being with you're fine.
3770K | ASUS STRIX GTX 1080 | DDR3-1600 16GB | CORSAIR 650D | CORSAIR HX 850W | CORSAIR H100 | SOUND BLASTER Z | ASROCK EXTREME4 GEN3