Heh, I kind of saw that coming.
Yoshi became my favorite first then Daisy became my second. It was when I was little, I seemed to like playing as Yoshi in Mario parties 2 and 3. As i became older, I started doing research about his appearances and other things. I believe I also liked him because I played the Yoshi series a lot (Super Mario World 2 and Yoshi's Story) when I was a little kid. He became my favorite video game character a long time ago.
As for Princess Daisy, it was kinda recent, I'd say 2012. I really liked her personality and I liked how well she paired with Peach and Luigi. She brought a little change to the main series plot-wise in Super Mario land, the two Super Mario Lands are really cool in my opinion. I also loved the scene in Mario Party 3 where she slapped Bowser hard enough to launch him like Team Rocket. That will always be my favorite moment in Mario Party 3.