Have owned a T2, a Leica CM (recently sold) and currently own two T3's.
If you are all thumbs the extra size of the T2 and CM is an advantage. For me I am dexterous with small cameras and the T3 is no problem. The T3 is smaller, it more easily fits in a coat pocket.
Image wise I think all three are excellent. The T2 while an excellent image maker, does suffer a little bit of vignetting where the T3 does not. The T2 is such a bargin considering cost/performance.
IMHO image quality probably goes to the CM - its more cooler and neutral than the Contax. However the T3 has a better viewfinder and image quality of the T3 is very close to the CM - I did'nt test them with same films/conditions so its my opinion only. The image quality of both cameras is really only apparent in enlargements, at postcard size prints you can't tell.
Some Contax optics have a reputation for making images with a slight magenta cast and I'd agree with that. More than one person has noted that 8x10 Contax images seem 3D and I just like the look and feel of that 35mm sonnar. They certainly are sharp.
In my opinion the T3 feels like it has a shorter shutter lag than the CM, again no science measuring and timing it just in the field useage.
All these camera's are now discontinued, sad, very sad.
Tim