Now let me see: rules of the air. Power gives way to glider (better not count on it, though), and glider gives way to balloon.....
Actual rule of the air, if it is bigger and heavier than you it has the right of way.
However, several times I have been seriously tempted to fly my glider - in a friendly, non-threatening way, around a hot-air balloon. With a friendly wave to the passengers....