same thing I recommend to anyone looking to purchase new gear. What are your ultimate diving goals, and what do you value?
Here are the things to consider
Are you interested in any sort of technical diving?
Are you interested in sidemount?
Do you value the ability to service yourself?
If yes to the above question, do you want to be able to be officially certified to service said regulators?
Are you diving primarily in salt water?
Do you dive at times of the year where the surface and/or water will be near freezing?
Are you willing to spend a premium for "Made in the USA"?
Do used regulators bother you?
Enough variables for you?
Here is what I look for
I will only buy regulators in pairs. I do cave and technical diving so almost all of my regulators are in pairs, backgas, stages, deco bottles. Also to consider if you are diving singles is that carrying the extra first stage with you even if you aren't using it will save you a missed dive in the event of a first stage failure. You can swap the hoses over to the spare first stage in 5 minutes and not miss the next dive. Much more important imho than the ability to get service globally unless you plan on travelling for extended periods of time.
I do not prefer piston regulators, and greatly prefer sealed diaphragms. The seal protects the internals from salt corrosion and while pistons can technically be sealed, it requires packing the chamber with silicone grease, and that's expensive every time you have service.
I require the ability to have accessible parts and kits for user service. It is a requirement for me, and caused me to sell many Apeks regulators.
Made in USA is nice, however mine are made in Sweden. CNC machines are CNC machines and it's the QC department that matters. Dive Rite, Hollis, Hog, and many others have proven that this is not to be of concern.
5 port swivel turrets offer the best hose routing for backmount singles, doubles, and sidemount and despite me not using them for some extenuating circumstances, they would be a requirement for me if I were purchasing new regulators.
Best bang for the buck today?
Cave Adventurers - Dive Rite XT Sidemount Regulator Package - Marianna, Florida USA - Never Undersold!
Grab that for $700, and get an extra HP hose for backmount and you have 2 firsts, 2 seconds, 2 SPG's, and hoses for backmount or sidemount. They have parts available to the users, though no formal training like HOG does, but they are sold by a company with a long track record of top notch user support.