I'll put in a 3rd vote Catfish Customs, but I'll likely try a GAS string for my target bow this summer.
I don't like to rip on a company, but I would not buy 60x ever again. I had two sets from them that creeped like crazy. I had to time my bow constantly. I installed the first set a month before a mule deer hunt. I verified tune the week before I left and by the time I got home 9 days later and the timing was off enough to move my BH POI 6" at 30 yards. Thankfully I never had a shot at a deer, but I did miss a coyote facing me around 25 yards. I'll never know if I botched the shot or if it was from the string/cables creeping.
I didn't want to make my opinion off of one set and most people I talked to had good luck with them so I got another set the following spring. This set never stopped moving either.
I installed the Catfish Customs in June and re-timed my cams after a couple weeks of shooting. I added a half twist and it was back to being timed. Shot a moose in September and a deer in November without having to touch them. I'd bet they are still on today.
The only positive to the 60x strings was I learned a lot about of tuning Elite's cam.