This will be the first among several parts where I ask you why you think certain characters within the Star Wars universe are such likable characters and potentially why you like them. I'm not a writer and I'm not really good at analyzing characters for their attributes. So let's being.

Darth Revan:

To me what makes Revan such a likable character is the long-lasting impact he's had on the Star Wars franchise as a whole. The legacy he left behind with his Holocron suggests an order of sith where only a master and an apprentice must be present in the form of the Rule of Two. Design-wise he is a very cool character. Many people already like Mandalorians for their concealed and awesome design aspects. Not only his armor but his lightsaber colors, blue, green, red, and purple signifying his constant turn from light to dark and back to light again. That is my reason why I like him and my guess as to why many other people like him.