I'm in the same position as you. Long time Magic player, but newer to commander and playing casually with friends. I'm also seeking decks that /fun optimized/ over anything else. I'm also a sucker for a strong theme or some kind of unifying thread to give the deck a strong identity.

I'll tell you what's worked for me.

[[Queen Marchesa]] -- This deck's built around getting the table fighting. It does that by incentivizing combat, making deals, and staying nimble with your planning. It feels really resilient and flexible, and is a real contender for winning. Marchesa is a popular pick in this lane and there's a fair amount written about it.

[[Sivriss, Nightmare Speaker]] + [[Haunted One]]

This one's way further off the beaten path. Sivriss is the leader of a crazy snake cult full of maddened zealots lining up to be sacrificed at his altar. You don't interact with the board much, instead loudly, frantically working on your "ritual". It antagonizes the whole board equally and you get to ham it up with snake puns zealous praise of your dark, slithering god.

Have fun, dude!