Not Clinton or Trump. I believe they have both disqualified themselves from receiving my support. When you decide who to vote for, you "should take into account a candidate’s commitments, character, integrity, and ability to influence a given issue". Both candidates fail those standards.
I am quoting the United States Conference of Catholic Bishops' document on faithful citizenship. They rewrite it every election season. Here is a link to the current version of the document. You can read the whole thing at your leisure. Let me quote two paragraphs.
42. As Catholics we are not single-issue voters. A candidate’s position on a single issue is not sufficient to guarantee a voter’s support. Yet if a candidate's position on a single issue promotes an intrinsically evil act, such as legal abortion, redefining marriage in a way that denies its essential meaning, or racist behavior, a voter may legitimately disqualify a candidate from receiving support.
In a situation where both candidates are morally repugnant, the document suggests "abstaining from voting" and "voting for the lesser of two evils" are morally acceptable positions to take. The document doesn't mention voting for a third party, or protest votes for fake candidates, but you could make an argument for either of those actions.
36. When all candidates hold a position that promotes an intrinsically evil act, the conscientious voter faces a dilemma. The voter may decide to take the extraordinary step of not voting for any candidate or, after careful deliberation, may decide to vote for the candidate deemed less likely to advance such a morally flawed position and more likely to pursue other authentic human goods.
Ultimately, it is up to the individual person to decide what they will do; "In the end, this is a decision to be made by each Catholic guided by a conscience formed by Catholic moral teaching" (37). Since I've ruled out both Trump and Clinton, my next step is to decide if I should go third party, or if I should not vote for a Presidential candidate at all.