Well, at least on the surface Aquinas simply glosses free choice as the ability (or corresponding act) to do otherwise, exempli gratia. For that reason, while Aquinas of course thinks the beatific vision is superlatively great, the willing involved in it is not something he would call free. Choice is only of means, not ends, so free choice is only of means, not ends.
But here are some qualifications: That Aquinas glosses freedom as the ability to do otherwise does not on its own show that he is a libertarian rather than a compatibilist. For the question is what kind of modality is involved here, and he never articulates a conception of determinism against which a modern libertarian would define free choice as not determined. And I wouldn't deny that ultimately some kind of "freedom as excellence" conception of free will can be extracted from Aquinas, but I think this involves projecting a different use of "free" onto him; it's not the way he uses the term, I think because he does not have the anxieties of contemporary libertarians.
My own belief, stated dogmatically, is that Aquinas is a libertarian, because he thinks there are cases where precisely the same apprehension of competing goods can issue in diverse actions, but his ground for the view is not the principle of alternative possibilities, as it is for many contemporary libertarians, because he does not quite hold that principle.
I don't think Feser has fully staked out his views on the matter, but my sense is that he is sympathetic to the Dominican (Banez, Garrigou Lagrange) views on nature and grace, which turn out to be fairly compatibilist. But all of that is above my pay grade.