Strong character customization, even allowing you to choose different music scores as a type of theme change for your character, you can build companions how you want as nothing is locked to a class. Strategic combat with some of the best ability synergy in the genre. Great writing with a lot of small details to give the world and quest more meaning. One of the rare games with a crafting system that gives you some good options. Offers a variety of ways to solve many of the quests. Divinity has some unique changes to common fantasy races and tropes. The conversation options specific to a certain race, gender, character, etc and being able to play as your potential companions allow for different conversation/quest options and endings.

Screenshots: https://twitter.com/Legolas_Katarn/status/994668948426711040
https://twitter.com/Legolas_Katarn/status/943979398646054912
https://twitter.com/Legolas_Katarn/status/995644208772857856
https://twitter.com/Legolas_Katarn/status/994670053873270784