What are good self-served networks to buy paid blog post in various niches?

I am looking for recommendations for networks that connect advertisers with content creators, namely bloggers, reviewers in a very price/performance transparent self-served way.

What is important for me is that the network is streamlined into a marketplace where I can pick from many different content creators of various sizes and niches and have plenty access to small creators as well. I don’t want to join ad networks where they expect me to dump 5k right as they tend to cater to larger ad spenders only.

I am not strictly against social media influencers as well but I am not looking for shoutouts or short mentions. I am also not looking for ghost authoring. I wish that bloggers write their own content, news, reviews, etc..

I would appreciate if you shared the networks you personally used or at least know that fit the above descriptions. If you use it as a content creator that is perfectly fine as well and would like to hear about your experience. Thank you.

You can try getblogged or intellifluence, though their fees might high.