Does it absolutely need to have a rail. If so, your options are the s3 or maybe attach a light to the glock.
If not, s2 has the conical barrel, and if you want the longer barrel s2 maybe you can order the AUS version.
I went through the same decision as you s2X v s3X at the start of the year. The s2 won as I prefer how the conical barrel locks up, slightly less slide mass and the fact it is a bull barrel.
If I ever buy a s3x, it'll be for the rail.
Im planning on adding a Hard Chrome s2 AUS with all the goodies to go with my Xtreme AUS in the future when funds allow.
Oh, and you can win with any of them ;-)