I have both. The T35 is a fixed 35x mag and not everybody can handle that, especially with standing and to a lesser extent kneeling targets. Optically it is better than the T50 which is perhaps no surprise as it's easier to make a fixed mag scope. But many folk like to zoom back to say 20x mag to take the shot as they get a better view of what the wind is doing to the grass etc near to the target.
The T50 has a mildot ret. The T35 has a plain crosshair with very small centre spot. Many folk will prefer the mildot to help with working out wind allowance etc.
I like the T50 but it pays not to use it on 50mag I feel. The image goes a bit flat and there's more contrast if you just back off to 40x or 45x. I use the same rig for bench rest and FT, and for that purpose the T35 is the better bet.