How do i know which one is the best or which one to choose?
it's all pretty much trial and error, for new people just getting started with mirc or irc in general it's probaly best to start with a full featured script such as the noname script that was previously mentioned by slade. there are others too, such as sysreset, excursion, and everyones "FAVORITE" invision just to name a few. just keep trying till you find one that suits you..
good luck!