I'll spare everyone's intelligence and not post the [sometimes extensive] resumes of those souls vying for the position as leader of the free world and simply stick to the question:

Libertarians,

1.) Who do you support for president in the upcoming national election and why?

And while we're at it:

2.) Which candidate has the strongest Libertarian sympathies or ideals? Does this influence your vote in any way?

3.) What factors besides party affiliation are determining how you vote in primaries and will determine how you vote in the general election?

1.) Who do you support for president in the upcoming national election and why?

I'm not bowled over by any of the LP candidates. I'd like to see Paul run as a Libertarian candidate, but I'm not optimistic about that happening. Most of the LP candidate's positions on immigration and non-intervention are too extreme for my tastes.
Unfortunately for an LP'er to make the national scene, they're going to have to make appeals towards the American-Idol-Centric population. The Libertarian ideals are just and worthy, but the sheep have to be weaned off of mainstream consumer politics. We're not going to have a viable national candidate until more local Libertarians are elected, and people start seeing the difference. We're not going to have a viable national candidate until the LP focuses more on Eminent Domain and the Bill of Rights, rather than open borders and ending drug laws. And we're likely to not have a viable national candidate until the LP convention gets airtime on another channel besides C-SPAN2. Of course, the conventions I have watched would probably turn off most prude, ignorant or confused Americans anyway.......
I'm not suggesting that the LP sells out and acts like Republicans and Democrats, but they need to soften the platform and soften the image.

3.) What factors besides party affiliation are determining how you vote in primaries and will determine how you vote in the general election?

The candidate that supports [within reason] the Bill of Rights, freedom and individual sovereignty is going to get my vote. I want a strong national defense but not an inter-national defense, and I want to end the tryannical reign that many city councils and other local governments wield over citizens daily lives in the form of permits, fees, codes, and restrictions. No one candidate will ever represent me on all of my issues, and that candidate is usually never from the two-party junta, but I will cast my ballot for whoever makes the effort in the above areas. I tend to remain undecided until the end of October, and that trend will likely continue this year.