My favourites (from the original series) are:
What Are Little Girls Made Of?"
"The Corbomite Maneuver"
"Arena"
"Court Martial"
"A Taste of Armageddon"
The City on the Edge of Forever"
"The Trouble With Tribbles"
"The Paradise Syndrome"
"Day of the Dove"
"Wink of an Eye"
The Empath"
The Mark of Gideon"
"Requiem for Methuselah"
I'm not sure if you ever got
Blake's 7 tv series. It has appalling special effects. But it is a twist on Star Trek. Terry Nation (who created it he also created the Daleks) takes the 'arrow heard' logo and turns it literally on its side. In it the Federation is a system that are baddies
Also he has an episode that is a complete rip-off of Star Trek's Arena excepting that two people from each crew are transported to the planet... and it's a battle against a 'baddie' human captain (as opposed to a 'gorn')
My least favourite character from any star trek series is Lwaxana Troi