i love (and am good at) catan and have multiple different win strategies. for me personally, it’s got great replay value because of the flexibility in strategies. if something youre doing isn’t working, or if other players have foiled your plans, you can quickly get back up on your feet. if you have multiple ppl who feel that way about it, it can be an exciting game til the very last turn.
house rules are also a fun way to change up the game play. depending on the group or the mood, there are a lot of ways you can adjust the rules and gameplay to make either a more chill or more difficult game play experience.
and finally, the expansion packs go fucking crazy. im not huge on them- some can straight up double the time it takes to finish the game- but they do add interesting elements that provide more challenges but also more ways to win.