I would just go to a good local guy and see what they offer you. Home Depot and Lowes both farm out their work to subcontractors. Why the hell would I want my work farmed out to the guy who bids the lowest for the job while they make a profit off of basically doing nothing???
If you dont have any recommendations from other locals who do siding work, go to a supply place and ask them if they were going to do work on their own home, who would they use?
Doing a little research into the type and differences is siding can make a real difference too. Just start doing searches on the Internet and should find a fortune in information.