futures trading, because futures trading is like playing gambling in my opinion. But since you are ready with all the risks, please try it.
When more the leverage, more the risk means what is the point of having 125 time leverage from binance' futures trading. I remember some forex platforms are providing up to 1000x leverage hence we can expect same high leverage on crypto markets as well. But, if we find some strategy to trade profitable in futures then we can make use such high leverages.
If volume is the selection criteria then bitmex must be the choice as they are the first one to introduce derivative trading in this crypto space (please correct me if I am wrong) and more than 70% of crypto futures trading are still happening there.