Lambic. Sour, sometimes a bit sweet...not at all bitter. Try a Kriek Boon.
In general, you want to explore some Belgian options. They have lots of beers with little to no bitterness and varying degrees of sweet and sour.
Oh don't give me none more of that Old Janx Spirit
No, don't you give me none more of that Old Janx Spirit
For my head will fly, my tongue will lie, my eyes will fry and I may die
Won't you pour me one more of that sinful Old Janx Spirit