For me, the appeal of dats are their size, patterns and personality (sometimes). First, I love how chunky and fat they can get. It's just cool to see a datnoid that looks wide like a fat guy lol. STs look cool to me because they're so wide and it's unique in fishkeeping to have fat looking fish like that.
I also like their tiger stripe patterns. If you can get a nice golden tiger with straight bars, it just looks cool. There are other fish out there with black bars, but none of them combine black bars with an orange or gold body like a good datnoid. Feels like you're raising the king of the river.
Their personalities are also pretty awesome (sometimes). It takes patience to raise them because they can start out being very shy. A lot of them hide, but when you can train them to not be shy anymore and they come begging for food, its like gouve achieved something as a fishkeeper. Its a cool feeling to see such a unique fish be active, it's like dating a girl who's hot and funny lol.