Guess I'm the unpopular opinion but I like the pansies, at least the hybrids. They're a little hard to mix with other flowers because they're so low to the ground (I've found cosmos work alright with them though) but they haven't changed that much for me. I've always admired the stripey orange ones, as well as the white ones because of the purple in the middle.
That said, blue pansies used to be my aesthetic flower and now I like blue hyacinths better (and I just discovered why, too - the blue pansies don't have white in the middle like they used to!). The basic color cosmos are pretty too. I like to call the yellow ones "sun cosmos" because that's what they were known as in WW and it made them seem special. Pink windflowers are also gorgeous, might be my favorite of the pink flowers!
And the purple rose color may be quite different in this game (more reminiscent of black flowers from older games) but I actually like it a lot. It's a welcome difference from the rest of the purple flowers that share a more blue-toned hue. And it makes me wonder if it's a color I should try on myself irl. ACNH is good for helping me shape my RL wardrobe