Ah yes the GFS pickups, real nice and bang for buck, currently have the mean 90s in my gibby sg and it is pretty sweet imo.
As for humbuckers, i have been a SD user for many years and they have never disappointed me, so i would recommend them. I currently have the 59' and JB combi in all my humbucker guitars, but if u r into punk/metal/heavy stuff, u shld try the distortion, invader, or blackouts but they r only good at heavy sounds imo. If u want versatility, i heard lots of rave reviews on their P-Rails. Hope this helps, cheers!