The biggest differences in pex are the means of connection. Uphonor is the only one that uses the expansion/contraction qualities of pex (memory) to make the seal. Every other one uses a crimp of some sort. The tool used to crimp usually needs to be either calibrated, or you need to use a go/no-go tool to verify it is crimped properly. This also means in cramped places, you need to access the joint multiple times, first to insert the tubing into the fitting, then to crimp, and then to verify the crimp is proper.
With a crimped connection, the ridges on the fitting can't be too high or you'd never get the tubing onto it, which means the crimp is what's squeezing things to keep the seal. It also means fewer ridges on the fitting that actually make the seal since you crimp between the ridges so the tubing is compressed against them. This also means placement of the crimp is critical as well as how tight it is.
On the expansion/contraction Uphonor fitting, the ridges are higher and there's at least an extra one since after inserting the expanded tubing to fit over the ridges, it collapses on them and creates the seal.
With the Uphonor system, you use the (moderately expensive) tool to expand the tubing and reinforment ring, then just slide it over the fitting and you're done. Placement isn't an issue...you just push the tubing up to the fitting stop and hold for a moment, then it's finished.
If you use the manual tool, you'll develop some strong arms. If you use the powered one, you'll lighten your wallet. You may be able to rent, or buy, then re-sell the tool to save money from others that have done the same thing.
SPeedwise, I'm not sure which ends up being faster, but I think Uphonor would be...I think it would be close.
In tight quarters, trying to crimp and gauge the crimp could be a real pain.