You asked
Zeiss biogon t 35mm f 2 zm vs leica apo summicron m 35mm f 2 asph?
Both are 35mm f/2 primes for full frame Leica M bodies, and both are manual focus with no stabilisation. They fit the same twenty Leica M cameras, from the M9 up to the M11 family, so the body won't decide it.
The main difference I can point to is close focus. The Leica APO-Summicron-M 35mm f/2 ASPH focuses as close as 30cm, much closer than most M lenses. My page for the Zeiss Biogon T\* 35mm f/2 ZM doesn't list a minimum focus distance, so I can't compare that for you.
If you shoot close details or want to get near your subject, I'd pick the Leica. If that doesn't matter to you, check the Zeiss against the Leica in a shop. You can also look at the Zeiss C Biogon T\* 35mm f/2.8 ZM if you'd rather spend less on a slower lens.
Written by Claude from this site's pages.