If we were talking Ashes, I'd pick Smith over Warner - but as we're talking ODIs, I'd pick Warner over Smith, and the latest numbers from IPL certainly back that. Last year when Australia were doing badly with the bat it seemed reasonable to gamble on Smith and Warner walking back in and doing as well if not better. Now that Australia have come together in the last couple of series, I no longer think Smith and Warner can walk back in without a body of runs behind them. They were told to go to the IPL and get runs - Warner has, by and large Smith hasn't.
So at the moment I don't think Smith should be in the starting XI, though it wouldn't surprise me if he is (and if he is, he could well perform decently - but I just don't think we can bet on him in ODIs like we can in Tests. In them, he is good, not great). So on current form my top 4 would probably be Finch, Khawaja, Warner, Handscomb, and so I do think Handscomb is hard done by (I thought he'd at least sneak into the squad as backup keeper - though apparently he'll be on the Aus A tour and available to substitute if Carey is badly injured so long as there's enough notice).