The best mouse cursor theme depends upon your liking and preferences. If you are a fan of Star Wars or World of Warcraft. you can get the respective set of mouse cursors. In case you like colorful mouse cursors, go for Rainbow Cursors. If you want the look & feel of Mac OS, mouse cursor sets like EVO Custom Cursors are good for you. I personally liked Cursors Manager a lot. It is a GUI-based software that comes with several mouse cursor themes to switch to.