Don’t get confused…
It all depends what you will do in the end. I know you are on a budget. And considering your function wish list I can show you the solution with the most functions for the lowest price.
XSI 5.11 Foundation: 500$
Covers modeling, rendering, rigging, and a few other things:
http://www.softimage.com/products/xsi/pricing_and_packaging/model_comparison/Default.aspx
If you need artificial landscapes on a budget… go for:
http://www.planetside.co.uk/terragen/
Here is even a XSI importer for that. (Did not try it out yet…)
http://www.guruware.at/main/index.html
With Zbrush you have organic modeling and texturing and UV generation and displacement map and normal map generation which fit’s to XSI.
XSI has a UV layout program and there is a free pelting tool for it if organic shapes are to complex for the build in UV editor.
Add the BHairy module from Ben and you are very well set for much less than 1000$ (not including Zbrush).
All runs on PC. You are on a PC right?!
And go, and try out XSI. It’s has a LOT of contents. There are MANY tutorials out there. But you have to SEE and USE it to make up your mind.
You have many more options for rendering. That’s a good thing and you can pretty much do everything you like. But first you have to understand those options. In Zbrush you model, press a button and there is simply NO WAY that your first model looks very very bad. IN XSI, the first model made me throw up becuase XSI is not setting a stage for you. You have to set it up. Then… it’s excellent. Till then it is exactly as good as your skills are. Having that written… I am experimenting quite a bit myself. But the renders do not make me sick anymore 8-).
Cheers
Lemo