Original Series: The diverse cast and intriguing often thought provoking story lines.
Animated Series: Didn't watch.
Next Gen: The Utopia we're all hoping for. A captain with actual diplomatic skill.
DS9: Greatest supporting cast of any of the shows. Ongoing continuous story arc that still is tops among the series.
Voyager: The greater exploration of the Borg.
Enterprise: Bakula as captain and a couple good episodes....and that's about it.
Discovery: Only watched the first episode. The reimagined Klingons turned me off immediately. Also, I don't want to see what happened before. I want to see what happened after the Dominion War. Leading into....
Picard: Great vehicle for Stewart's acting chops, but the time jump and destruction of Romulus are handled clumsily.
Lower Decks: Haven't seen.
Prodigy: Haven't seen.
Strange New Worlds: Haven't seen, but as above...I want to see the future...not the past.
An ideal show for me would be a series that showed the immediate aftermath of the Dominion War and the rebuilding of the Alpha Quadrant....but that ship has sailed, I fear.