For me it's season 4 of TNG. It's the season I grew up watching on repeat. I like every episode which is rare for an entire season. It also has a great verity of episodes. You get a good amount of sci fi, mystery, political intrigue, and the thing season 4 is most known for, deep character development. Best episode for me has to be a tie between Drumhead and The Wounded, but I also have a soft spot for Future Imperfect.