As singers, I would list Liam O'Kane, Steven Geraghty, Michael Horncastle and Tom Cully as favorites.
Having been to a few meet and greets, my favorite personalities are
Tom Cully - who made me feel appreciated at my first meet and greet (it was supposed to be the other way around

Ralph Skan - whose disposition is as sunny as his smile
Zack Lockett & James Threadgill who are quite lively and worth seeking out should you find yourself at a meet and greet.
Had I not had the opportunity to meet everyone in person, I would have chosen Flynn and Kavana who are both so expressive when they're singing.