I have used Suntek (regular, not the Reaction) on a previous car before, and couldn’t really tell the difference between that and Xpel. I think some reviews have said Suntek has a bit more clarity, but honestly probably not noticeable difference.
I was actually very interested in Suntek Reaction, but the shop that I wanted to get it from was booked out for almost a month, and I really didn’t want to leave the car unprotected for that long. But if I had the option, I likely would have gone with Suntek Reaction. The shop had a Taycan that was fully wrapped in Suntek Reaction and it looked great. More shiny/glossy, and surface was more slick than regular Suntek. Once you put ceramic on Xpel or regular Suntek though it basically looks and feels the same. The concern I had was how long the “ceramic” properties would last on the Reaction. With applying ceramic on Xpel, you can always reapply when needed.