Well, the most rational argument is that he isn't a Democrat
That's not a rational argument.
The rational thing to do is to look at all of the qualities of a candidate... their policies, their personality, and pick the one that you think would best benefit you or the voter. Rejecting a possibly superior candidate just because they belong to the wrong party is not rational, its foolish.
and the second most rational one is that he isn't Hillary.
Another irrational argument. Just being "not hillary" does not make anyone a superior candidate.
The third is that he will crack down on illegal immigration,
Hurray! An actual policy position that can be examined!
Ok, lets consider that policy... Trump wants to "crack down" on illegal immigigration. Part of that will be a wall, which will be extremely expensive and ineffective.
You see, claiming a candidate is good because they will deal with a particular issue is only relevant if what they'll do is actually beneficial. Spending billions on an ineffective wall is not better than doing nothing. Its worse.
It's kind of amazing that proposing something as rational as building a wall on a border where there are a million illegal crossings a year is considered somehow beyond the pale.
The wall may cost ~$25 billion by some estimates, will be largely ineffective (many illegal immigrants arrive on legal visas and overstay, others arrive by air or boat or other ways, and even the ones who cross by land can simply use a rope), and can negatively affect both the environment (affecting migration habits and isolating sub-populations of various species) and the lives of people who live there (the existing wall has subdivided some communities, since it can't follow the border exactly; its unlikely Trump's wall will be any different).
If someone says "lets spend almost $100 for every tax payer for something that doesn't solve the issue its supposed to but will cause widespread problems, I'd say that that's a pretty irrational thing to propose.
