Should I go with a back inflate? I was looking at Sherwood's Axis and Tortuga. Any recommendations between the two, and the Avid? Also, is an Apeks the way to go over a Maximus? I was also looking at the SR1. How would that compare to an Apeks20.
There is a lot of debate on this topic, however the only person who needs to be happy with your choice is you.
A BC is just a bag of air that has a strap to hold your tank. How it works is mostly dependent on how you use it.
If you're properly weighted, it will be a bag containing very little air, and whether or not it's back-inflate, jacket or a backplate & wing will matter very little on a normal recreational dive with a single 80 Cu Ft tank.
A good jacket style BC is position neutral and will not tend to roll you one way or the other in the water or on the surface. The down-side is that it will not tend to keep you horizontal either, so it's a little more sensitive to proper weighting and trim than a back-inflate.
A back inflate will tend to keep you horizontal in the water without quite as much tuning as the jacket, however it requires a little more care on the surface to keep you from tilting forward. Neither is a show-stopper. It's really a matter of preference.
I dive both a SP Classic for classes and warm water single tank dives and a BP&W when diving doubles. Our shop has taught over 35,000 divers over 40 years or so in jacket BCs with no problems related to the design of the BC, so if you go with one, you probably won't be sorry.
That said, if you go with a back inflate, you probably won't be sorry either. They're just a little different.
Now there are a couple of catches. Really big guys and "curvy" women do better with a BC that has little or nothing in front. This would include some back-inflate BCs and almost any Backplate & Wing with a simple ("hog") harness.
Good luck! Don't rush into anything. SCUBA equipment lasts a really long time, so make sure you pick something you like, and not just something the shop wants to sell.
As for regulators, I'd go for something appropriate for the worst (coldest & deepest) conditions you can think of yourself diving in, even in a few years. The only thing more expensive than buying a good regulator is buying a bad regulator and then a good one.
Terry