I prefer the Cad-Technik because it doesn't displace the rear sight, and I like the idea of having my iron sights in case of a scope problem. (But it's actually never come up yet.)
It claims you can remove the scope (two piece mount, one piece comes off with the scope) and it won't lose zero. Some people report that didn't work for them, but I have two of them and it has come true with both on several different rifles I have used them on.
It does raise the scope higher than any other. I use a Beartooth Comb-raising kit on one gun and a replica sniper cheekpiece on another and that answers that for me.
I haven't tried any of the others but this question comes up with some frequency and the S&K and the Armalon seem to be consistently spoken well of. Some people also say the ATI is as good but I think I recall slightly more people disappointed by the ATI than by others.