Monahorns and m/,
Larry's explanation largely fits my view. However, I'd like to add another point. When I cast a ballot, I don't pretend that I'm voting for an emperor who will have absolute power. I put the candidates in the context of the office they're seeking as well as the checks and balances that will exist around him and her.
Davis can be as pro-abortion and anti-voter ID as she wants, but unless a Republican-dominated Legislature is willing to revisit those issues (which it most certainly is not), her views are irrelevant. Same goes for the Medicaid expansion. I oppose expanding Medicaid (which Davis supports), but Davis will have no ability whatsoever to make that happen. Because of that, I put little weight what she (or Abbott for that matter) think of those issues.
As for illegal immigration, they're a wash. Neither she nor Abbott will do ****. Like other Democrats, she wants the state taken over by Mexicans so she won't have to appeal to moderate. Like other Republican leaders, Abbott has big business' balls firmly entrenched in his mouth, and they don't want to stop illegal immigration.
Here's what I do know. For the last 10+ years, there has been an ethical stain on Texas government that has permeated the Governor's office, the Legislature, and the Texas Supreme Court. Rick Perry may have been its ringleader, but one-party rule (and therefore nonexistent oversight) has allowed it to become ingrained into Texas law and political practice. The branches of government are supposed to be somewhat adversarial. That's what encourages them to keep each other in check. When you have one-party rule, that adversarial relationship goes away, and corruption runs wild. Do you think a Democratic governor would have gotten an "Enterprise Fund" from a Republican Legislature? Hell f-ing no.
If Greg Abbott wins, that ethical stain at best continues and likely gets worse. If Wendy Davis wins, it gets smaller. Does it get smaller because she's a better person than Abbott? No, it gets smaller, because the branches of government charged will start to care about ethics again. It will be for partisan reasons rather than a good faith concern for the public, but it will happen. That is a big plus.