Enterprise is definitely my least favourite though, although I will admit that I did something I never did with any of the others and stopped watching somewhere through Season 2. You're not the first person to say that it got much better in Season 3 so maybe I should try to catch up on what I missed.
Not giving anything away here, but they introduced a much more continuous story line that pretty much started from the season 2 finale and ended at the season 3 finale. There were some stand alone episodes within the season that diverted fromt he main storyline, but not many. When season 3 first aired here on sky, I was glued to my seat every monday night.
This storyline changes the mission from being a banal exploratory mission and fumbling around through space trying to find friendly aliens, to a military mission with a goal to save humanity. It's very focused and fast paced.
I think what put me off the last series was a succession of very poor scripts at the outset with the main characters doing inane or outright objectionable things but unlike for example DS9, where characters also sometimes had to do questionable things, there is little reflection on what has been done, no remorse. Everything the captain does is justified by the end of the episode because he's 1) Star Fleet 2) Human 3) the Captain and 4) Human. The crew also regularly engage in one of two activities: staring at T'Pol's tits & arse or telling T'Pol that she's wrong (reason for being wrong - she's not human). She spends a lot of time being lectured by humans half her age and intelligence for using things like evidence & logic where she should have used things like gut feelings and intuition.
I also found those things annoying. Especially the gratuitous scenes in the decompression chamber. There was one scene where Hoshi is crawling through a ventilation shaft and as she leaves the shaft her shirt comes off. It was comletely unnecessary and did nothing to progress the story.
I managed to turn a blind eye to it however, because I liked the way they had to deal with problems when they were alsmost universally outgunned and out-teched. I also liked the way they demonstrated how and why certain things, that you see later in the star trek universe, come about. Such as the prime directive, star fleet etc.
Something I despise is the way in which they use evolution. The writers seem to think that evolutionary change can happen over a period of hundreds of years and inevitably leads to a species becoming progressively more intelligent.
they could bring back nostalgia races such as the Andorians
They did that exactly. They brought back the Andorians. They also brought back the tholians. But I understand where you're coming from, they invented an army of new species when they could have brought back some old ones.