I like to use Mario mostly, as I feel like the game was designed around him and he's the most challenging to use. I also like to use Toad and Blue Yoshi in occasion though, especially in Toad Rally. As I have yet to buy the full version, I don't have access to the other characters.
I use Peach, Daisy, and Toadette more often. I love how it has Peach playable which is something that NSMBWii and NSMBU should've had years ago.
Also I would suggest renaming this topic to "What characters do you use in Super Mario Run?" that way it doesn't end up being a duplicate of this topic https://www.marioboards.com/index.php?topic=37561.0 .