It sounds like you should fit into either binding, but will fit into the FKS easier since it starts lower. At that point its just personal preference. The STH with the driver toe and the FKS are IMO the best mass produced binding on the market right now. I have pairs of both that I really like, but I would personally say go for the FKS on that setup.
Sth 16's have a better toe piece, fks have a better heal piece. Both would be good, if your going to be skiing a lot of pow then i would get the sth 16's just because fks are annoying as hell to put back on in pow.
im 155lbs and have sth16's and absolutely reccomend them. I have them on my one lifes and they are great. best binding i've owned. They drive the ski very well because the AFD on them is very wide. the toe peice is the the greatest because you can dial it in exactly too your boot. everything about them is great!! oh and they are burly as fuck!