Have you tried Model United Nations (MUN)? I highly suggest it if your school (or maybe one nearby) has a team. My son really enjoyed it. There are inter school competitions as well as national. It is also something that you can continue on a college level as well. Perfect for anyone interested in foreign relations, politics and history. Basically you act as a delegate (as part of a team) of a particular country and defend or promote your positions for given scenarios.
There is an element of debate but this is very different (my son didn’t like debate either but really enjoyed MUN.)