Buffy the Vampire Slayer
I ignored the first series and only started watching part way through the second season. It has a lot of action, frequently in the form of Buffy kicking vampires (or demons) in the head. Sometimes this seems repetitive with the latest evil arriving in Sunnydale just to be swiftly dispatched. What's surprising is that most of the time it stays fun. Each of the characters have background and motivation that goes beyond the individual episodes and they change over time.
Some seasons are better than others with different bad guys and themes being developed. Season Three is one of my favourites but all have their good points. Off the top of my head some episodes to watch: Once More, with Feeling to show what can be done with words (or song in this case) and Hush to show what can be done without words.