Both Turbo Tax and Credit Karma are good for filing your income taxes and I used to mainly use Turbo Tax for many years for filing my taxes and it was very easy to use when filing taxes.
Filing Taxes myself without Turbo Tax was a nightmare and I had to hire the filing of the taxes out before I discovered Turbo Tax.
Then when Credit Karma started allowing you to file taxes through them and offering their Credit Karma Tax filing service I gave them a try.
And after using Credit Karma for filing taxes I found Credit Karma to be a bit easier than Turbo Tax and prefer to now use Credit Karma for filing my income taxes.
But both Credit Karma and TurboTax are good tax filing services but I prefer to now use Credit Karma versus Turbo Tax.