The Sharkbite fittings vary in price depending on what type of fitting you need (T, L, etc). I chose the Gatorbite fittings because of the ease of use and how simple they are to replace should I ever have to do so.
The clamp rings are quite a bit cheaper but you'll need a tool to clamp them to the PEX. I didn't use these because it was crimp dependent and I didn't want any leaks once I turned on the water pressure.
I had zero leaks after installing the PEX with the Gatorbite fittings and have since had to replace 1 inner sleeve on one fitting.
You figure out the leaks by putting a pressure gauge on the line and put a bit more than water pressure on it and leave it on while constructing...
