I get orchids from a big-name Hawaiian grower once a year and most of the plants I've gotten from them have been potted in pure charcoal. That's another hot, wet environment like yours, so it might be a vote to try charcoal. I repot all those into bark/charcoal/perlite mixes on their next growth cycle, because I want more humidity at the roots than that, but I'm growing in my house in upstate NY, very different conditions than yours.
I also might mention one rock substrate you didn't -- diatomite. It holds less water than bark but more than lava; it's lightweight; it definitely doesn't break down fast. People use it a lot for Australian dendrobiums, and I'm thinking about getting some to repot some of my more temperamental cattleyas. It seems like it would be less likely to rot roots than bark but would still let me keep fairly even moisture.