For our uses, I like the low cost of the Amazon units. If anyone asks, this is what I recommend. Now if I were an EMT, would I want to carry one on the truck? Probably not, but for our use I think they are fine. The low price gets someone with limited resources a 25LPM regulator for minimal outlay.
I have a WT Farley too. Great, well-made unit with a 40LPM option but they cost a bit more.
The only regulator I've had trouble with was a one I purchased on eBay.....the yoke bent after a few years of use and wouldn't stay sealed to the tank outlet. I robbed a couple parts off it and in the trash it went. I figure I got more than 20 bucks worth of use out of it.
With any regulator, keep spare seals around. You'll need them eventually.