I think it depends partly on how much space you can devote to the tortoise and what kind of environment you can provide.
Any of the three species you mention can get 12" or larger. Such a large animal is going to require maybe 25 or 30 square foot minimum. And they would all do better if you could provide some outdoor space. If you have good weather year round, then you would have a large area out in your yard, and a small area indoors for bad weather days. If you have cold winters, you'd need a large space both indoors and out since the tortoise would need lots of room for the winter.
If you are going to keep the animal outdoors, you should consider your local environment. If your local weather (at least during the warm months) is rainy and overcast, that won't work for a desert tort or a leopard. If it's extremely dry and hot, it would make keeping a red foot more difficult.
Finally, it may not be easy to legally obtain a desert tortoise (I'm assuming you meant one of the American desert/texas/gopher tortoises). I think all are protected and require special paperwork and licences. Forgive me if you already knew that.
If you don't have a lot of space for a tortoise, I'd suggest a Russian tortoise. Not too large (usually less than 8" ), tolerant of a wide range of temperatures, and also tolerant of a wide range of humidity as long as they aren't kept under damp and cool conditions. See www.russiantortoise.net for more info.