It's no huge biggie either way, but personally I'd recommend alcohol:
- You're going to countries with a relatively warm climate - gas in pressurised containers has more potential to go "boom" than alcohol.
- If the gas does escape in a confined area it makes the entire area highly flammable, again moreso in a hotter climate. If it's alcohol, you can get away from it.
- Alcohol doesn't need any fancy adaptors or such things, you just buy it and pour it in, end of. (Note: I'm not aware of whether foreign gas cylinders are different and if so what adaptors might be required, but with alcohol this problem just isn't there.)
- ..and because it doesn't need any fancy adapters that cuts down on the amount you need to carry, weight wise and bulk wise.
- Alcohol stoves are simpler and therefore generally more reliable too, the trangia being a prime example.
That's not to say gas doesn't have its advantages, it's less messy than alcohol (just screw in and go) and usually gives a much better heat output, therefore cooking more quickly.
Note that I'm not aware of how widely available alcohol / gas are in the parts of the world you're going to, so if one is much more readily available than the other, that may (rightly so) heavily influence your decision.