The OP (of this question) only asked about AA, DL, and UA. So it was in that context that I mentioned only AA and DL as being potentially 1.2 miles per dollar.

UA (UACO for three more weeks) may be 25%, but that's on top of a horrible base net rate of 0.5 miles per dollar spent (because of the 2:1 base transfer ratio). The OP (of this question) was asking about the efficiency/wisdom of earning airline miles through a hotel credit card, and thus while a 25% bonus on transfers to UA may be true, it's basically irrelevant, because it still doesn't cure the 50% devaluation you start with (compared to not just the UA card but also Ultimate Rewards linked to either Sapphire Preferred or Ink Bold).

Meanwhile, while I realize that US is currently in *A with UA, and thus US miles can be used on UA, that may or may not be the case a couple years from new, depending on what happens with its attempt to merge with AA. (If such a merger did happen, it's much more likely that the combined entity would end up in OW than that two of the three remaining major legacies in the US both being in *A and none in OW.) That's why I never mentioned US as an alternative to UA, since the OP didn't ask about US.