Canon EF 24-70mm f/2.8 L II vs ???

Of the three primes you mentioned, only the 85mm f/1.8 really holds up well on a full frame camera. The 28mm f/1.8 has soft edges and CA even on a crop sensor camera, and the 35mm f/2 is great on a crop camera, but, suffers from soft edges on a full frame.

The EF 24-70 f/2.8 II is the real deal, and would be my choice.