I’ve use TurboTax for the Mac for years, and though it can have problems and not be the cheapest, I’ve kept using it. It’s rated fairly high among software reviewers, and does everything I need for business taxes with multiple Schedule C forms, etc.
Most tax software features a different variation on the “interview” structure, where the software walks you through adding info and making decisions. I don’t much use that feature anymore, but go straight to the forms in TurboTax and work from there. I let TurboTax do all the calculations and let me know when I’ve forgotten something.
I don’t use any online tax prep software; I do everything on my Mac and store all records locally, too. I guess I’m a little old fashioned that way.
If you want to try out tax software, see if the producer offers a money back guarantee. Other than than, check the reviews below before you buy. You can read reviews at Cnet.com for CompleteTax Deluxe, TurboTax Deluxe 2010, H&R Block At Home Deluxe 2010 and TaxACT Deluxe Edition.