Well to compare apples to apples, none of those promos are giving FB miles. UX owner is a bit of an eccentric who does promos like this all the time - I had a long post about the PepePhone program a few months ago - but they aren't related to FB miles at all. He's just giving away seats on nearly-empty flights (i.e., Q class).

The PepePhone deal looked much better, because it earns "UX bucks" that you can spend on any fare, including miles-earning and business fares. Unfortunately they only offer these UX bucks for normal domestic calls - no roaming nor data charges - so it's pretty much useless.