I wouldn't get any of them but that might be just me. I just think for APSC format that's tad long (I know, I know...120/135 is the longer end of the traditional film portrait range...). I prefer shorter lenses for that purpose, 43-50-55-58 and that would be my recommendation...
Anyway, it depends what is important for you. They are both really sharp, thay have both very good OOF (especially 1/2-1 stop down), Sigma seems to controll CAs better, Sigma is cheaper, Sigma is 2/3 of stop faster. Also, Sigma is 2-3x the size and definitely heavier, Sigma will not resell for as much as FA77 (just in case you realize you made mistake
), 77 has SMC (some say Sigma's new coatings are just as good but I have some doubts), 77 definitely has a lot of character in the way it renders, 77 isn't very fast to AF (I'd guess Sigma's HSM is faster), and 77 has inadequate hood to it's FOV on APSC.
In short:
It's either sharp, fast, large and heavy with fast AF
Or sharp, quite fast, small and lighter with slower AF
Luckilly choice is yours, I made mine
(had and sold 77...)