Before downloading Meaningful Stories it was definitely Happy. Way too overpowering emotion. It's kinda funny how they call Fine the default but sims get Happy from every meaningless little thing that Happy was the true default IMO. Like good for you that you can find happiness so easily but everyone grinning around like they are high 24/7 is kinda unsettling.
After the mod I think it's Bored and, situationally, Uncomfortable.
I have a snob sim who's constantly bored even when doing things she supposedly likes. While I appreciate new animations that make her visually stand out, you can't even do anything with this emotion. I checked it out from the Wiki, it only lists the source, not any effects. Great.
Uncomfortable more so for specific situations because while I do think think it's a realistic emotion, the situations they'll get it sometimes just make the sims seem so fussy/entitled that it annoys me. Like, wow, one counter in your kitchen is a bit dirty or there's one puddle of water on a bathroom floor and you're flipping your **** over "unpleasant surroundings" and refuse to do anything because of it? Hah, their little minds would explode if they visited any real life home that actually looks like it's lived in.