The Current Rules
Right now, I am leaning toward using a modified version of Robert Fisher's Classic D&D Injury Table for Athanor. I like it because it seems to feel right. I dislike it because it adds one more table to roll on, and damn it, I hate memorizing or looking up tables. It isn't bad, and it's a lot less than I have done in other games I have enjoyed. But I like winging it.
It's still my number one choice.
The Full-on John Carter of Mars Rules
On the other hand, I like the idea of getting simple. And simple is what Edgar Rice Burroughs (and many pastiches) seem to call for. The heroes of planetary romance (with the notable exception of the first book of the Green Star series by Lin Carter) do not get killed. They get threatened, the get knocked out all the time, they get imprisoned, enslaved, fed to monsters in terrible dungeons. But dead? Not so much.
This would mean that a hero at 0 hit points is unconscious. A villain may do something to ensure the hero's death (but usually won't), but as a rule, the hero is out cold. He will revive hours later on his own, but may be awakened with a few hit points by an ally or by tears of sorrow or joy from a beloved holding his unconscious body.
This is nice and simple, but doesn't it reward recklessness and stupidity (which, if we take John Carter as our example, is fully within genre) and take away some of the threat of danger in the game (not necessarily....)