I have to say that from all the 3D programs that I've had access to (my dad is a designer) Maya has been the easiest for me to catch onto.

Also, in the version of XSI that I used, it required a ridiculously large (larger than my res. of 1024x768)...which is way too big for me to actually model anything. But the rendering caps are a lot better..your choice but I say maya ^__^