Best software for tax?

Yes.

Excel

TurboTax & FreeTaxUsa are both highly recommended here within Google's internal forums. Several people have compared both and received comparable results. H&R and TaxAct come in often in discussions too and seem to be good with slightly less intuitive UI. Credit Karma works for basic situations but seems to not support many common scenarios.

Taxact. Don’t give your money to intuit. They are evil.

Try credit karma, its free and pretty good. Pain if you have lots of stock transactions