I been using someone that advertises and pays extra to advertise more on bhw, and their quality options are what I need in terms of budget ad comprehensiveness. I am happy adding and enhancing work that has been researched already, as I consider myself an expert already in most niches I ask to write about, so its easy. I canceled my ai writing services, and prefer to pay someone to do my homework, so I can enhance from it, and I find its a good idea to no matter the writer, tell them you want a few references for further reading and where they get their info from.
My top tier tip to you is to create a mind map for each subject niche you specialize in, and work to make that the central content generation machine that you enhance from your own homework and from writers you hire, you'll find it much easier to be an expert in the field, as all that really takes is knowing where everything fits, and a mind map, is the same structure as your brain to help organise it, lol