The colour of magic isn’t highly rated by anyone. Most discworld fans will tell you to skip the first two books and don’t really count them. I hope you didn’t skip discworld based on that. If your willing to give it another go, most fans suggest starting with Guards Guards! as the feel of discworld is well established by this point and the Watch sub series is a fan favourite.

There are 5 main sub series; the Witches, Death, the Watch, Industrial Revolution and Rincewind. Rincewind is the least rated. You can read them in pretty much any order but each sub series is recommended to read in the reading order:

https://commons.m.wikimedia.org/wiki/File:Discworld_Reading_Order_Guide_3.0_(cropped).jpg#mw-jump-to-license