Best Software?

Asking the 'professional' opinion of those on this forum, what is the best homework supplement software for a Calc student? Wolfram has a product called Calculus WIZ, but it is apparently not rated very well. Likewise, Calculus Solved! seems to be rated well but only works up through Calc 2. I am not a visual person, this is why I am asking for a software that will help me visualize the problem, especially for 3D applications. Software that provides reasoning behind steps is desired. Thanks.

Note: I am NOT trying to just find a homework solver. I want a more firm grasp on the subject, and to do that, I sometimes need extra reasoning and conceptualization of the problems in question. Thanks!