Script suggestions are not the greatest idea - there is no 'best' script I might add, a script is as good as you make it, or one which suits your needs. Some sites review their scripts and give it a rating, aswell as provide comments for users. Some of them include:www.mircscripts.orgwww.mirc.netwww.hawkee.com
There are also lots of screenshots so you can see what the script looks like before downloading. A lot of people like Peace And Protection script as it has lots of feature protections, written in good English, no awful colours and adverts etc. however, for someone looking for mp3 players and colourful popups/entertainment, it's less suitable. It's also known to be quite incompatible with other addons should you wish to load them at a later date and support from the original author has been stopped - I believe there is a 'new and improved' version as someone has picked up where the other author left off....The original by pai is downloadable from mircscripts.org.
Obviously, a Google search always helps too!