TurboTax, hands down! For those using the simple 1040, 1040a (prolly the majority of us). I enjoy: the built-in interview feature that interacts like a personal tax preparer, all the forms I've ever needed are already in the software, it lets me play with the number to see "what if", I can update the tax return as new records are received or revised, and it generates my state tax seamlessly. I know it will process returns involving property, divorce, small business, yadda-yadda, but one would prolly want to have professional help in matters involving the big bucks. Oh, and it will review and pinpoint the dumb clerical errors.