I have the Boon Flair and don't know the other highchairs very well, but I can vouch for the Boon. It's very easy to clean and I love how it wheels around and the pneumatic adjustment of the chair. It's also pretty small and the red one I have is kind of cool to look at (I have tops of FP items and it is rather nice to have one sophisticated, though still fun colored, baby item). The tray is not big, but I don't think it needs to be.
The only issue I can think of is that the straps are very loose on a little baby. However, the tray has different slots so you can wedge the baby in very well, but the straps themselves are not much help until baby is bigger. I wouldn't use it without the tray yet for my baby, but it's fine when the tray is inserted.
DD1 9 yrs old 12/2011
DD2 7 yrs old 01/2014