Let's see if I can summarize for you.
1) The most important thing is choosing a brand that you can get serviced locally, or finding a mail-away shop that is reliable (and there are several). Finding a shop that you trust (and we all learn the hard way) is KEY! If you feel you're not getting a straightforward answer, ScubaBoard is a great place to ask questions. There have been comments about do-it-yourself service and second hand regs. Me, I haven't bought new in a long time, but I trust my own service more than a local dive shop. You find a lot of folks like us in this forum. But thinking realistically, self service takes a lot of dedication to detail and a modest investment in tools, not to mention being able to access proprietary parts.
2) So really, we're looking at best bang for the buck new stuff, or quality used gear where the cost of service to ensure performance is accounted for in the total cost.
3) So here are my 2psi. IF it can be serviced locally, and IF price is not even the second or third consideration, then a major manufacturer selling a new regulator is the best way to ensure a) performance, b) likely more consistent service (because they're common), and longevity, because they've been around. What brands? Aqualung, Scubapro, Atomic, Mares and Sherwood. Again, what brands are serviced locally? No, I'm not an Oceanic fan, either.
4) That said, there are legions of great regulators out there that can be had for a song on eBay, IF you have someone to bring them up to snuff. Most all of them have an issue, however. And if it's just an overhaul, you'll get by with an additional $150 in service costs. If they need parts? $50-200 on top of service and your purchase price. That's how I got Atomic T3 regs for $400 and then fixed them like new for an $800 savings. But peace of mind comes at a price.
If you look on eBay for a brand that you can get serviced, and choose a reputable seller, and the pics are good, and you budget for the service cost, you can
really score.
5) But the hidden gem in all this is the alternative manufacturers. Deep6gear.com is a ScubaBoard darling. Why? Because Chris (
@cerich) will sell you parts. Chris will service your gear quickly for the cost of postage. Chris will train you how to do it yourself. Will they be here in 30 years? Well, look at HOG/Edge, which is another choice. They're still here (perhaps because Chris played a pivotal role before he started Deep6). Or consider Dive Gear Express and Dive Rite regs. ALL of these offer HUGE price point advantages because manufacturing costs are only a small part of the equation. Word of mouth counts for a lot, which is part of why Deep6 is continuing to succeed. They're quality, and they're responsive. Look at their Facebook site. Who would respond to you in real time from Aqualung or Scubapro?
You can spend $450 and have great gear from Deep6. You can fret that they'll still be here in 20 years, but you'll only be out $450. You can buy Atomic or Scubapro for $1300. And you can continue to pay double for parts and service because that's their business model. Meanwhile, you'll continue to get great service from Deep6 until you're ready to spend beaucoup bucks for Scubapro, and you'll end up not being able to see a difference if they're both serviced equally.
You can learn to do it yourself and get vintage gear or used top-of-the-line stuff. But your tools and parts cost will eliminate part of your advantage. The satisfaction will be huge, however. As will be the time investment.
I haven't answered your question. But I hope I've pointed out that buying "brand name" comes at a cost. And due to all the competition, the performance difference is zero in the recreational realm. Actually, even in the high performance realm. If you look closely, (but you'll never hear Chris saying this) you can spot a Deep6 logo on a regulator of one of the top rescue divers in the Thai cave rescue videos.
I dive Deep6. I dive Atomic. I dive Scubapro. I dive Poseidon. I dive Aqualung. I dive Sherwood. I even have an old HOG and a Hollis that I like. The cavers seem to like Dive Rite and Halcyon. Apeks is huge in Europe. Oceanic is quirky to service, as is Cressi. Mares clings to some old designs, though quality is good.
What can you get serviced, reliably? That is the question.