Oh man, so hard. OK I’ll try:
1. Probably the Abduction Arc (Duane Barry/Ascension/One Breath). I had the VHS when I was a kid back in the 90s and and I watched it to death. I also love Sein Und Zeit/Closure even though I know a lot of people hated them.
2. There’s SO MANY. Darkness Falls, Detour, Chinga, and All Souls spring to mind.
3. I’m a huge fan of the funny episodes. Rain King, HTGSC, Bad Blood, and Syzygy all stand out.
4. For a specific moment, probably Post Modern Prometheus. For a whole episode: I’d say Je Souhaite. I’d have probably been OK with it had the series ended there.