Is there a site where you can compare manufacture to manufacture about regs? Something similar to buying a camera at Best Buy where you can compare the Canon to the Nikon to a Minolta. Or does it boil down to personal preference and comfort, then $'s and cents?
Probably not a single source of comparative data. But, there are more than enough threads on SB about the features that users dislike or prefer (balanced, diaphragm vs piston, environmental seal, adjustable second stage, yoke vs. DIN, etc.) to compensate for that, and going from manufacturer site to site is probably a less useful endeavor than researching on SB, and no more (or less) objective. There are a substantial number of manufacturers of reliable regulators - ScubaPro, Apeks, Zeagle, etc., etc., etc. Each manufacturer's line will reflect levels of performance, so you can get a low end Apeks, Zeagle, ScubaPro, or a high end. But, they are generally all functional and safe. Differences in performance at the different ends of the spectrum are most notable under more extreme conditions - e.g. at depth and in colder water - and are often a matter of perception as well as reality (you will find brand zealots on SB, on dive boats, in local shops). Local service availability is, as several have noted, probably one of the most important factors in a purchase decision. ScubaPro makes great regs, for example, but if your LDS isn't a SP dealer, parts will be harder to come by or at least slower in coming. A number of people will spend an almost inordinate amount of time worrying about making the ONE right choice, and there simply isn't ONE right choice. A process of investing 40 hours of research, to 'save' $75 as a result, seems like an odd value equation - you spend that much on dinner - but that is just my bias. So, do some SB research and visit a LDS (or two), to ask specific questions, then make a purchase and go diving. And, no matter what you buy, you will always find someone who will second guess YOUR decision after the fact - 'Why in the world did you waste your money on XXXX? My YYYY is so much better and I got a great deal.' Simply smile, and say that yours was free because you 'registered to be an equipment evaluator'.