THere's a third choice - Uphonor's expansion rings. THey all work, I'm not sure there is a big difference on the crimp rings. I prefer the Uphonor's system, but it does require a more expensive tool to install (a tubing expander rather than a crimp tool). WIth this system, you insert the tool into the tubing, expand it, slip it over the fitting, then the PEX (with the reinforcement ring) collapse over the fitting. PEX has memory and I like the fact it makes the seal on its own rather than relying on it being compressed. But, done right, they all work. By expanding the tubing, there's less restriction at the fitting, too.
PEX is made in one of three methods, and designated as -A, -B, or -C. -A is the most flexible and the only one that can have a kink repaired. -B and -C types require you to cut out the kink and insert a fitting. Plus, -A bends to a smaller radius, often requiring fewer fittings.
