This is a tough question because I don't think you'll find too many people who have been able to spend much time on all 3 (or others). Most folks will own one of these, it might be the only one they've ridden, and justify why they chose that one - you'll get very subjective responses. Off the top of my head, the only person I can think of who could give you an objective overview would be DC Rainmaker.
With that said, I think one thing that should be considered is what kind of software you might plan to use with it. Being that these are all ERG/power trainers, I'm assuming you want to use them with something like TrainerRoad, PeriPedal, Maximum Trainer, RacerMate One, or PerfProStudio. There's also the CycleOps Virtual Trainer, but you didn't list the CycleOps PowerBeam Pro here, so I figured you weren't considering that. Elite also makes some interesting-looking power trainers (
http://www.elite-it.com/...ainers/real-trainers). Regardless, with the exception of RacerMate One, these various software packages can potentially support any of those trainers through ANT+, Bluetooth, or via virtual power, but you would want to double-check.
I don't know if that really helps at all.
Travis Rassat
Vector Cycle Works Noblesville, IN
BikeFit Instructor | FMS | F.I.S.T. | IBFI
Toughman Triathlon Series Ambassador