Don’t know if he’s my absolute favourite, but I love Timicin from TNG’s S04E22 “Half a Life”. He’s a good, dedicated and kind man who would have been a great long-term partner for Lwaxana Troy, but for the fact that he is about to commit ritual suicide as he’s about to turn 60 as a part of a culturally enforced practice called The Resolution.
Played by David Ogden Stiers, he has great chemistry with Majel Barrett, and their relationship is a believable one. He’s a man torn between challenging his society for the chance to keep living in order to save it (he’s the lead scientist trying to stabilise their sun) while finding love with Lwaxana, and not rocking the boat and simply doing what’s expected of him.