If you skip the temporal cold war and the intro, Enterprise was great.

Most of the characters had a reasonable amount of depth, none of them were terrible. The worst characters were forgettable but not cringe-inducing (Mayweather and Hoshi). More importantly, the characters developed across the series, which rarely happened in the other Treks (Tom Paris and the Doctor on Voyager being notable exceptions).

The writing was fantastic sci-fi: full of ethical dilemmas and effective at displaying how different other cultures could be, and how challenging it might be to find common ground. The overall message of the series illustrates the importance of cooperation and diplomacy, highlighting how vital it is to bridge the gap between our differences to work towards a better future. To me, this is the central concept of Star Trek, so maybe I over-value the series for focusing on it so much.

The CGI is pretty bearable, but I will concede that the Suliban (aka the green oatmeal aliens) shape shifting will not age well.

I'd trade the last two seasons of DS9 for two more seasons of Enterprise.