I used C-35 for grafting my Shiranui budwood. From everything I've read it performs well with many mandarins and yields trees with big production from a young age that are semi-dwarf to full sized, depending on the cultivar. Also a very large citrus nursery is trialing this variety on C-35. They have been in business for decades and know their stuff.
It really depends on what you are doing with the trees, in ground, in pots, etc. I would also consider Trifoliate for semi-dwarf, Carrizo for large size, or Flying Dragon for dwarf.