What data loggers are the most versitile and best for a wider range vehicles (cars and motorcycles)?

what is it you want to datalog?

in my experience you're best off getting a decent diagnostic machine that does live data of sensors etc

that wau you can select which sensors you want to log and go out for a drive, i use VCDS for vag and delphi autocom to log certain things such as lambda sensors etc

ideally your diagnostic tool will have graphing function and that way you can see if lambda is working ok, ie front should be sine wave, rear should be flat line

There are alot of good ones out there. What vehicle are you trying to log?