There is really nothing that complicated about Pex.
Once you pick a system, best to stick with one manufacturer. There's regular potable water tubing that is cheaper, and there's more expensive tubing like Pex-al-Pex, Onix, ThermaPEX primarily specced for radiant heat. For regular water supply, stay with regular like AquaPEX.
The ProPEX system uses expansion tool. Its pluses are that since you expand the tube to fit, the fittings are thicker/sturdier, with better flow. Also, since you work the tube before putting it on its fitting, it is more convenient in tight quarters. But then, a little advance planning should preclude the need for crimping in tight quarters.
The crimp system uses copper rings and a crimp tool, usually with interchangeable jaws for every size. The CinchClamp system (most DIY-friendly, IMO) uses stainless clamps. One size tool fits all clamps, there is a positive 'click' when clamp properly locks, and clamp system is easiest to alter - just cut the clamp tab. Even though clamps cost twice more than crimp rings, overall difference is negligible (bag of 100 1/2" clamps $30, bag of 100 1/2" rings $15)
One thing to remember about PEX tools is that while they are costly, their resale value on ebay is almost 100% of retail.
PEX plumbing is generally a 'home run' system. Meaning you want to avoid elbows, tees, and all that - for every fixture, you run a single length of tube between main manifold and fixture stop valve. use
bend suports where tube makes a turn. Use nail plates where tube passes through a framing member if closer than 2" to the edge. At fixtures, it is best to install
drop ear bend supports.
Drop ear elbows are another option, but they usually mean your PEX connection is inside a wall.