im a plumber, and use pex and copper all the time.
Copper is best, if supported rite, insulated ect. Wich most pumbers dont do.
Pex is fine, the problem with the other brands being sued is from.
People using the wrong crim rings with a different brand of pex.
Poor installation., wich covers everything else...
Obviously "pex" expands and contracts, so if you "butcher it" in like said above you'll have problems.
Uponor is good but there problem is, like said above..expantion and contraction. With heat you have this. Uponor have plastic and brass fittings. People use plastic fittings of heat pipe/ they crack.
The other brands youse brass fittings/very thin. And although "i" havent had a problem with them, i thingk they would over time(just how copper corrosion over time from ground watter)
So "i" use "pex" but the uponor/ wirsbo stuff; and with the bras fittings youll never go wrong. The brass fitings compared to the others is 2x the thickness.
Any ? ask and i could let you barrow a tool kit from me obviously if you pay shipping and a deposit, because there expensive,