In this new digital age of online distribution you have worldwide exposure at your fingertips. You have a lot of choices of whom you will have distribute your music. Since, most artist only know of these two companies (Tune Core and CD baby). I will talk about the pros and cons of each.
CD baby is initially more expensive for their Pro Distributions package running you close to $60 for the distribution of one song. But they allow you to retain the ownership of all your ISRCs and UPCs upon purchase and CD baby comes with a lot of collection and enforcement perks.
Tune core is initially cheaper for distribution but charges you more for the back end of the distribution of your money once the funds come in. It is $9 for the initial distribution and $10 for youtube collection, $2 for Facebook collection and $75 for a publishing fee. Now they do their job very well. But this might not be necessary if your not selling a lot of music right now.
Also, if you allow them to code your music. They essentially own the rights to your music until you pay your publishing fee and cannot collect your money until you pay that fee.
So as a musician it’s up to you and reading the pros and cons of each company and what situation works best for you.