A lot of people here use Solidworks. A lot also use Rhino. Rhino is the preffered app for more organic shaped or freeform objects, but can do just about anything. No parametrics, though. Solidworks, and others like it, excel at mechanical type objects. Also has the added benefit of assemblies, which Rhino does not.
I'd stay far away from Maya, as it's primary function is animation, and you'd only use a small percentage of the software for modelling, but you might want to look at Alias' Studiotools.
http://www.alias.com/eng/products-se...ls/index.shtml
Before spending any money, it's always a really good idea to play with demo's. Especially when the prices get higher.