I would go for Blender (you said you had a super PC) if it mustn't be Amiga. Blender evolves all the time and it's pretty amazing what it already does. The learning curve is huge I guess but I'm sure it pays off in the end if you're in for serious rendering work too.
I played with it's sculpt tool a lot and it's just amazing. I've used imagine in the past too and it was good enough back then but today I wouldn't bother when there's alternatives.
