I've used H&R Block for several years and wouldn't switch. It seems as if any time I have a question, the self-help links in the software have the answer. It's very user-friendly, but I also have the feeling that the program is fighting for me -- to make sure I don't miss any possible deductions or tax credits. I have a feeling of confidence when I've finished my taxes.
Pros: Maximizes refund, Easy to import documents, Fast
Struggled with program after I completed Federal and started my state form. Question was if starting new form which I was for my state. So the program deleted my completed Federal taxes and I had to redothe completed form all over again.