Start with TNG. The first season is slightly campy, but some good episodes. Season 2 gets better though skip shades of grey, it’s a clip show that we don’t talk about. Season 3 is when rider grows his beard and things get awesome.

Then when you’re done with that you can do DS9. Its slightly darker, basically bring uplifting in times of war and has amazing episodes.

Then there is voyager. Its more uplifting again but the writing really isn’t in oar with the previous two

Then there is “enterprise” which is darker again, not a very great first seasons though it gets better

Then you could do TOS but the visuals haven’t really held, of course, as it’s the 60-70’s

Don’t watch the post 2000 star trek, though, it’s awful. Discovery is full of spiteful characters, cringe writing, all flashy nonsense bling bling CGI and a lot of plain hate. Star trek Picard was so horrible that it ruined TNG for me. I watched TNG and DS9 episodes multiple times per month, all my life. I watched Picard about a year ago, and I haven’t watched star Trek ever since, it is THAT bad.

All the post 2000 shows have been made by people who dislike trek and only we’re there to use it as a political platform (literally their words). If you want to watch modern star trek, watch “the Orville”, it’s made by Seth McFarlane who also plays a character in Star Trek enterprise. the guy is a huge star trek fan and wanted to make a star trek show. When he couldn’t, he made the Orville and it’s all that TNG is, but modern