I think keyloggers are better personally, because they are made to be keyloggers.
Sometimes the loggers in RATs are poorly coded/not focused on as much because there are so many features in a RAT. I've never had clear logs with RAT loggers.
If you want to be able to see if you have gotten a slave anywhere you want to, buy a keylogger. If you're inexperienced with technology like RATs, buy a keylogger..
Other than that buy a RAT. You can see what your slave is doing, they come with their own keylogger, and you can shut off their computer or disable their java and so forth.