Well, I personally use 3DSMax with general modelling work, and Bryce for abstracts (because its really good at them). 3DSMAX itself is very very powerful, but its interface is not very intuitive, so initially you are up against a learning brick wall. Once you pass that, though, you'll be able to do some pretty nifty stuff. Bryce, on the other hand, is far easier to use, but lacks the sheer power of 3DSMAX (something surely reflected in the variation of the price of the two applications). I'd personally try both and see what you can come up with....
PS. Just as a side-point, you can download Maya learning edition totally free of charge. It puts big watermarks everywhere, but still gives you a good idea what its like to design in 3D. Maya itself is by far the flagship 3D product - ludicrously expensive, extremely powerful, and bloody hard to use...
