TOS is my sentimental favorite because there were no others when I first saw it, at a time when I was just getting into science-fiction (Thanks to Star Wars.). I also like the characters best. But I find ST:NG more watchable. There are TOS episodes I have no interest in seeing again. When TOS was good, it was very good, but when it was bad, it could be very bad. I think the worst ST:NG episodes are just mediocre. Also, it was truly an ensemble show, which allowed for a greater variety of stories.

I think the criticism that the crew got along too well is valid to a point, but they were in a military setting and behaved in a very professional manner. If you watch them again, you'll see the conflict was often between the Enterprise and the alien guests of each episode, with Picard often raising his voice to them. The conflicts among the cast of "Deep Space Nine" and the ongoing stories turned me off at the time, but I may consider trying it again, thanks to streaming services.

I liked the "lost in space" concept of "Voyager," but after a while its creators seemed less concerned with that, and the idea that part of the "crew" was anti-Federation, and just seemed to be recycling NG stories. I haven't seen much of "Enterprise" (It was aired by a network not offered by my cable company.) and none of "Discovery" or "Picard" yet.