Man, sucks you didn't like Come Back Again that much. I believe that song is what modern K-pop needs more of actually. Upbeat energy, rich and authentic instrumental, ear-catching hook...
I like Bad quite a lot actually. Not on the same level as Come Back Again for me personally, but its blend of hip-hop and dramatic orchestra worked naturally and the hook is quite catchy.
I also believe you shouldn't judge a group based on just a few songs. That doesn't make sense lol. It's best to dive deeper AND listen to each song multiple times. You never know if any of these songs will grow on you.
a big part of the appeal is the commitment to extreme emotions pulled off by talented (and very unique) vocals. it doesn't land for everyone, though, so don't sweat it!
that said, i wouldn't necessarily equate having the most Youtube views as being their "most popular" song. it's more a result that kpop itself was growing on Youtube throughout the 2010s. it's a little subjective, but i'd prob go with either "Be Mine" or "The Chaser."
Come Back Again has a heavy Michael Jackson inspiration, I guess not everyone likes that style of music generations later 😂 I think you might appreciate Man In Love if Dangerous is closer to the styles you like.