Hi i know everybody says forti , but im wondering about compilation with insight and vamp gaze on my sorc. Treachery for me is hmm medium because in fast MF runs ,need time to works well .

yes, that is the biggest argument against treachery. it is great as soon as it pros but only mediocre before...
if you want direct dmg from your merc > forti
if you just use him or her as an aura slave > stone might be good enough and a lot cheaper

Stone is decent, but in time, you'll just miss the big damage boost and the chilling armor bonus from fort, or the ias boost and potential fade from treachery. Too good bonuses to pass up even for the big defense stone can provide. It's not better. But try for yourself if you want.

Stone used to be better when fhr was more important because act 2 mercs have shit for fhr frames.

fort