If your pro-life stance is one that you value above all else, then veer away from candidates like Mitt Romney and Newt Gingrich, for they both have shaky stances on the issue (though Romneys has evolved).
Newt Gingrich is rock solid, pro life.
People who tend to be more socially moderate might flock to candidates like Romney, Gingrich, Paul, and Huntsman; putting issues like abortion and gay marriage on the back burner.
Fact check needed on Gingrich.
You make some good points. I would add that almost anything called a “voter guide” is some shallow textureless “checklist” type analysis that refuses to take into account the most important factor: which is what candidate has the chance to actually get things done that you agree with.
In other words, you might well choose someone who agrees with you 90% of the time but has a lot of accomplishments over someone who agrees with you 98% of the time but does not have the success record.
The idea that you have to either go with principles or politics is simply a false choice. It is the lazy cop out. I refuse to cede the premise.