Need help choosing a role/champ.

Hello, I'm a Gold 1 player (climbed quite fast, started season 8 at silver 4) and I want to get all the way to Diamond 5. I believe the biggest thing holding me back is my lack of devotion specific roles/champions. This season i've "mained" mid, jg, adc, and supp. I play everything except top. I want to narrow it down to 2 roles, preferably mid/jg. I'd like to know what the best champions ATM are to climb from Plat-Diamond in the mid lane/ jungle are. Thanks for any input :) p.s: I'm fine with maining supp/adc if you believe that it's a good way to climb