Town Hall attack survival bonus
The purpose is to protect your TH. Therefore if the TH survive an attack there should be an extra reward.
A few ideas for typical reward.
1. In life if you survive there is selebration and every one spirit is up. Maybe a 10% boost of builders for a day as reward
2. Loot cart can go to clan castle and perhaps % can be a bit higher if your TH survived
3. Every one in town help to finish one building which means 1 building can be finished imideately.
I'm sure there are lots more ideas on how te reward a TH survival and I think it will add a lot of fun