Oh god, i’ve been avoiding this question only because I wouldn’t even know where to begin !!! There’s so many incredible accounts I admire, most of which i’m sure you are already aware of! To start, as far as accounts go any art i retweet is usually someone i follow and admire very much! I also follow a great deal of art accounts as well. I think the most effective way to get a request done is to search for artists with commission slots open! That way you can have a good one on one conversation about your desires and you’ll have a better chance of getting what you’re looking for! Off the top of my head, I’m not sure of any accounts that take requests as I do (though i’m positive their are), but i don’t think it hurts to reach out over retrospring if you have an idea, as long as you are polite and understand that artists not actively offering requests may have other priorities or reasons to not take requests!
Forgive me for not offering specific accounts I recommend, there’s so many and the list would go on and on, and I especially wouldn’t want to make a post and realize i’ve forgotten someone very important to me!