I like EasyCryptoBot https://easycryptobot.com/ because I can implement my strategies very easily. However, they offer only Binance and only a couple of technical indicators to use, but it is quite new and i hope to see more soon.
It is free and open source - which means it is easy to check (if you have some javascript knowledge) that the bot will not hijack the account. Also it can work without connecting to an account and just show trading alerts or to backtest.
Here is a video with the basic functionality: https://www.youtube.com/watch?v=-r-H3l92AG4