If a voter (myself, for example) is looking for the closest thing to a strict-constructionist candidate, for whom should he vote if not Cruz?
So on that issue alone I'd vote Trump, only Trump is credible on immigration.
Next I'd think about all the unconstitutional agreements made over the last few decades and who supports them and who doesn't. Again Trump appears to be much better on constitutional issues than any other candidate.
It is important to look at actions, not just words. Professional politicians are very good at saying the right words to get elected and then doing the opposite in office. Particularly Senators that only have to run once every 6 years.