I would avoid Sharkbite-style fittings. I've personally not used them, but people on the Airstream forum have found that the only thing separating you from disaster is one O-ring which tends to get eaten over time. Some of these fittings are getting better, using two O-rings, but the issue does still remin.
The Flairit fittings don't use O-rings, so seem to be something good for the long haul.
Of course, the best way to do it is to use Uponor PEX tubing and expansion fittings which stay on for good, but the tool for those is very expensive.
