So we have loosely three camps: GOPe candidates to attract the #nevertrump cuckolds, Trump-friendly Republicans to solidify political legitimacy with the skeptics, or populist Democrats to pull Bernie supporters. Each category has drawbacks and no individual from any of these groups jumps out right now.
Among the GOPe stooges are Cruz, Rubio, Kasich, and we can include Fiorina just because she's a woman. Kasich was always the Democrats' Republican choice this primary cycle, and Rubio is a token hispanic who is surely willing to bend his ideals for career advancement.
More pro-Trump Republicans include Christie, Huckabee, and Sarah Palin, who are fairly prominent politicians, as well as Ron Paul, Rand Paul, Jan Brewer, Pat Buchanan, Ben Carson, and of course Jeff Sessions. Sessions would be the audience's choice, but he lacks any crossover appeal that Trump doesn't already have. Huckabee and Carson have their constituencies, but who knows how many extra Evangelicals or blacks they would pull away from Hillary? Buchanan and the elder Paul are too old, and Rand just seems like a fool. I haven't heard much about Jan Brewer apart from being a nationally-recognized female Republican. The only other one of those who I can think of is Palin, who has baggage and more celebrity capital than political capital. Maybe Michele Bachmann sneaks into consideration too.
The third camp of VP possibilities are the softer Democrats (or third-party idealists) who could find common ground with Trump's populism platform. We already listed Jim Webb as an obvious frontrunner here. Bernie must also be a possibility, as weird as that sounds. It would burn a lot of bridges with the stalwarts but surely open a lot of new avenues to votes. I expect Trump's team is making this particular list much longer. Probably the mayors of big cities and governors of blue states are worth crossing off manually, since their campaigns may have been ambivalent on some of Trump's talking points. Look out especially for token minorities and women.
One more consideration is the possibility that the GOPe shills run a third party candidate, which would shift the weight of the pros and cons list. Trump can't get too far ahead of himself planning out his legacy because his enemies in DC have not yet fallen in line. I think this also adds to the likelihood of the eventual VP coming from that third group of candidates.
