You can buy a RAM pickup truck with a VAST # of different configurations and options. That doesn't stop the dealerships from picking one and putting it on display.
There's actually probably a lot more agreement on a "standard" BPW config (for single tank diving) than even what there is for a "standard" pickup truck configuration.
And since I'm here posting anyway, may as well stir the pot a little bit....
As I posted previously, I think the Hydros Pro has a lot of advantages over a BP/W for single tank diving.
But, I pretty much never dive my Hydros Pro when I'm diving a single tank. Because, what IS better than the Hydros Pro is a Freedom Contour back plate (made by
@Eric Sedletzky) and a good wing (I prefer the VDH Argonaut wings, myself). The Freedom plate takes away a couple of the advantages I cited for the Hydros Pro. The Freedom plate rig is just as stable and just as comfortable as the Hydros. And it's stainless steel, so I generally need no lead at all when using the Freedom plate rig.
I can't say the Freedom is as convenient. I mean, the Hydros has no crotch strap to don, and it cinches down quickly and easily in every dimension. A BP (of any type) that is setup Hogarthian style (the only way I run any of mine) has a crotch strap to do up, and if you are changing between warm water and cold water, it's more time-consuming to adjust to fit just right. But, once the BP is setup to fit the exposure protection you're using, the difference in convenience is negligible. The crotch strap only takes a few seconds to affix when kitting up.
With the Freedom plate being equally stable and comfortable, I am happy to use it over the Hydros (despite it's other slight disadvantages like convenience and slower drying) because, one, there is nothing on my BP/W rig to break. No plastic anywhere. No hinges. No shoulder straps that might rip. And, it is so much more streamlined than the Hydros (even with the travel waist belt). For warm water, I use an 18# wing on my Freedom plate. Diving with it is like having nothing but a bare tank on my bank. The tank is closer to my body and the drag from the wing is about the minimum that it could possibly be. The Hydros holds the tank further out from my body and the wing is quite a bit bigger.
The Hydros Pro is a top of the line BCD. But, if you can get one, the Freedom Contour plate is nicer (to me, anyway).