TOS is very dated and can be hard to watch at times. You definitely have to be appreciative of the camp and low production.
TNG holds up a bit better. It’s not an adventure show though, and the first season has some real stinkers. I’d say it’s a good starting point to watch the first 3 or 4 episodes then go to season 2 weeks give that a shot. If you like how it’s going then go back and finish S1 and keep going.
DS9 is like tng but also has a bit more edge and does some good deconstruction of the pure optimism of tng. It is still optimistic but also has some cynicism I love it. I don’t think I’d like it as much without a good tng backbone though.
Overall 90s trek isn’t going to really give you a lot of adventure focus, unless you watch the movies. It’s strengths lie in the morality play and the collaborative problem solving, and the idea of a bright future. Picard kind of shits all over that idea of a brighter future but to each their own, I can see why some people would like it.
That’s a common refrain from fascists and it’s not actually historically accurate. Not a great thing to parrot imo