I think she's my favorite character of the mainline Super Mario series despite her being introduced in SMG1. I like the fact she's this OP queen of the galaxy with a sense of fashion.
I enjoy how she's been in more and more Mario games as a playable character, and I look forward to playing as her in Mario Party 10 as much as I play her in Smash.
Watching this video was what made me ask this question:
https://www.youtube.com/watch?v=Rwu1Qiwa4F8