I will vote for Romney, because Obama will do NOTHING about illegal immigration.
Romney has at least promised to do something about it. It is an easy choice to make.
I agree with you that illegal immigration is a bad thing. Legal immigrants actually pay taxes, and people hiring them actually have to follow the market rates when hiring them. So my problem isn't with immigration as such, I have no problem with reducing the restrictions we have on it, but illegally immigrating here (Other than refugees from Cuba) should not be tolerated.
That said, it is not the issue I am going to bank my entire decision on.
I'm fiscally conservative, usually socially libertarian, and non-interventionist for the most part on foreign policy. Fiscal and foreign issues would usually trump social ones, except for a couple of social issues I consider to be extremely important. (Mainly abortion [pro-life] and surveilance [Against it, give us our doggone privacy])
Neither candidate is fiscally conservative. Although I would give a slight edge to Romney on fiscal issues. Not much though. And that's only guesswork. I don't really know what he'll do. He could theoretically be alot like Obama on economics, or he could actually move towards the right significantly. I'm guessing closer to Obama than to Reagan, but time will tell.
Neither candidate is anywhere resembling "Non-Interventionist" but Obama is less likely to go to war with Iran. Romney might not, Obama might, but I'm guessing my odds are better at avoiding such a war with Obama, and that is a pretty big issue for me (I do NOT want to be drafted into a war, nor do I want to see several times as many people killed as Afghanistan/Iraq.) So Obama gets a slight edge on foreign issues, for me. Not much, but slight.
Neither candidate is particularly good on surveilance. Both are in favor of increasing surveilance and decreasing privacy. But at least Obama got rid of SOME of the Patriot Act. Romney would probably favor the whole thing. So slight, VERY slight, edge Obama (Both candidates are full of crap here even more than the first two.)
Abortion, neither candidate is sincerely pro-life so its a wash on this issue. The only thing Romney might do better, in real life (Not based on what he says) is be more against later-term abortions, but I don't suspect the issue to come up again, so its a wash.
So ultimately, its pretty much a wash anyway. I prefer Obama over Romney for three reasons...
1. He's only got two terms, and he's already served one. So that's four more years. I don't expect a good candidate from either party, but I would think the GOP is marginally more likely for a libertarian-leaning person such as myself. Romney most likely loses us that chance in '16.
2. Obama is predictable. Romney is not
3. Obama will probably have the House and Senate opposing everything he does. Sure, he'll use executive orders, but that will only drag him so far. Romney may well have the entire government united behind him, and that's a scary thought.
Note: this doesn't mean that I like Obama, at all. I can't vote this year, but if I could, it would be third party. But if I had to pick one of the two, four is less than eight, so that's it.