It took me a while to find a couple of good, natural English writers. The problem is that for native English speakers, it's VERY easy to spot someone who isn't. I've lost count of the times someone has tried to tell me they're native speakers and I glance at their profile and call their bluff straight away. The thing is though, I've had some decent articles off people on there, well researched and with some good info, but unfortunately when it's written by someone who doesn't have English as their first language, it really does show.
If you're not concerned about that then there are a few decent writers. If you want native English then it's a slog. My advice would be to look for those with videos on their profile. There are a couple and I've had some decent work off them.