Do you think there are dictator-selection procedures that don't have either set of failure modes (selecting for looks/promises to loot the commons/lack of leadership, selecting for power-hungry tyrants)?

Only a single one: a great actually-benevolent-dictator, with a good insight into people and lots of rationality, personally selects his successor among several candidates, after lengthy consideration and hidden testing. But, of course, remove one of the above qualifiers, and it can blow up regardless of the first dictator's best intentions. See e.g. Marcus Aurelius and Commodus. So, on a meta level, no, there's likely no system that would work for humans.

(I think that "real" democracy is also too dangerous - see the 19th and early 20th century - so either some form of sophisticated rule by committee or a state of anarchy could be the safest option for baseline humanity.)