Trump’s appeal is he is not politically correct. With the sissy-fication of the American public, Trump is gaining popularity with those sick of the politically-correct atmosphere of the U.S.A.
On the other hand, Cruz or Rubio will not win the nomination because they are establishment republicans. The republican establishment has been in full control of both the house and senate and has yet to move to reverse Obamacare or any of Obama’s executive orders. Therefore, conservatives are seeking a candidate that is not a career-politician or establishment republican because there is no more trust in a GOP candidate to do anything except continue liberal policies.