I'm currently reading this. https://perfectdailygrind.com/2018/05/why-are-some-coffees-more-acidic-than-others-a-brew-roast-guide/
It might help you in deciding which green coffee you want and how to experiment with it. I hope it gives you ideas like it does for me, I'm currently experimenting with pan roasting. If you want to invest anyway, I'm not recommending you do many pan roasts but you might wanna try at least one, especially since it's super cheap to accomplish.
Those represent the extremes of my last pan roast. If the middle bean is 50%, most of my roast was beans at 40%.
The leftmost one tasted a little fruity and chocolatey. The middle one tasted baked and toasted and the rightmost one tasted more like burnt toasts, the only one with a frank bitterness.
Ethiopian Kaffa Anderacha. 100g for 9m20s at 65%. Cracking started at around minute 6. When I was happy, I went to shake it outside in the sieve. I was aiming at a light roast but realizing that it's not a very even method, I went and made sure even the greener beans had time to get a little tan. I think I'll use 50g instead next time.
Advice is super welcome.
I just prepared a cup using the James Hoffman daily driver aeropress recipe as soon as it was cool. I know I should let it degas but I wanted to experience the freshest cup possible as a base for later comparison. As is, to my understanding, it tastes planty, caramely and neither too acidic, astringent or bitter. Really nice cup.
I agree with the comments here. Personally, the sweetest coffee I have tasted is natural processed Kaffa Anderacha, which managed to keep some sort of cherry flavor no matter which roast level. I think you might get a real feel for sweetness in coffee with a quality natural processed coffee from Africa. The only issue here is that it was pretty tart, or sour\acidic, which, to my understanding can be alleviated by having it a little darker roasted, but that might also degrade the cherry taste.