Haven't used any of the trading bots. It's good to participate manually, because price variation happens periodically and only a human mind which is focused on the specific subject makes the right prediction and the trading in a better way than the trading bots which are developed by the same human minds.
there are certain actions that you can not do manually and need a bot. one of them is what OP is asking for and that is Arbitrage trading. there is simply no practical way of doing that without a bot with high speed calculations and high speed internet to execute orders.
what you say is true about traditional way of trading which is buy low, sell high. that can always be done manually and without a worry in the world!
