"i have a business with an 1120s form which program is best for me to buy"
If you simply need to enter a K-1 that you received from an S corporation, you need an copy of TurboTax Premier or Self-Employed if you want to use an online version of TurboTax or any CD/Download version of TurboTax.
In order to prepare a Form 1120S for an S corporation, you will need a copy of TurboTax Business. You can purchase TurboTax Business directly from Intuit or from a reseller, such as Amazon (links below).
https://turbotax.intuit.com/small-business-taxes/
https://www.amazon.com/TurboTax-Business-Software-2017-Efile/dp/B075BCZLT5/ref=sr_1_1?ie=UTF8&qid=15...
NOTE that you will also need a TurboTax personal income tax preparation product to complete your individual income tax return (TurboTax Business can only be used to prepare income tax returns for entities).
