With the Trek TV shows, the two best are The Next Generation and Deep Space Nine. Watch the Original Series if you're interested because, well, it's the Original Series. But be warned that a good chunk of it simply isn't very good. Voyager has its moments, but peters out towards the end. I can't say I've watched more than about five minutes of Enterprise--the stupid theme song was enough to make me decide not to give it a few months of binge-watching.
The original cast films are a mixed bag. The Motion Picture is iffy. Wrath of Khan is great. Search For Spock is interesting, The Voyage Home is iffy, The Final Frontier is flat-out awful. The Undiscovered Country is an OK end to the run. In reality, it's Khan being magnificent followed by everything else ranging from just good to horrendous.
For the TNG films, Generations and First Contact are pretty good, Insurrection is OK, and Nemesis is awful.
The first reboot film is great, the second is a fun watch, but with total mess of a plot and a sloppy rewrite of Khan.