I’ve dabbled in leverage trading. It’s decent with BTCC, they offer up to 100x, which is pretty high risk, so you need to be careful. As for customer service, I had an issue once where a transaction didn’t go through. It was nerve-wracking, but their support team resolved it within a day. They were quite responsive. If you’re okay with occasionally slow withdrawal times and a bit of a learning curve, BTCC is a solid option.