Trump, for better or for worse, is known to most people through television, hence his high numbers. Not sure if his poll numbers will actually translate into votes. Ben Carson and Carly Fiorina, on the other hand, I beleive their supporters and overall numbers seem to be genuine.
Cruz is one of my favorites, but I'm starting to think he's never going to get that much higher in the polls. Rubio is the strongest one, but right now he's a bit lost between the big three (Carson, Trump, Fiorina). Scott Walker is out, sucks but overall he was barely a presence. I hope Jeb and Huck are next, 'cause they ain't going nowhere.