I can't really comment on too many programs as my experience is limited to poser, povray, wings3d and a friend's old version of 3dsmax I played with for a couple of hours. Personally, I prefer povray (and poseray to convert poser characters). It's an excellent renderer (and free), but some of the features requires learning it's scripting language. Everybody has a different opinion, but I don't think it's really difficult to learn - just need a different mindset. All things considered (and this probably doesn't help much, but...), I think the best is whatever you are most comfortable with. I've seen some pretty amazing images from just about every app out there.