Daisy is a boring character, to be honest, and is just filler for spin-offs. Overall, I don't care for the character since I think there really isn't anything to like about her. On the other hand, I don't exactly hate her either since she doesn't have anything that makes me hate her either.
She's just... there. There really isn't anything special about her. Even her debut game, Super Mario Land, she's just a Peach rip-off, having the exact same damsel-in-distress role as her. They could have used Peach instead of her back then and nothing about the game would change in any significant way.
Hell, you could even label Daisy's sprite in SML as Peach, it wouldn't make any difference.
Again, she's just there and it took a tennis game with 2-on-2 matches released around a decade after her debut to bring her back and it was for the sole purpose to serve as filler so Peach could have a partner, which is essentially the same reason why Waluigi is a thing.
Admittedly, I do find Waluigi to be funny because he does have some wacky characterization, even zanier than Wario. Otherwise, he's as much filler as Daisy is.
However, I do admit: for a filler character, she does have a quite... interesting... fanbase. I do wonder how such a one-dimensional character manages to have such devoted fans.