Larger sensor than 24x36 would be nice.

6 sides would have the least waste, but then you would lose the proper 24mmx36mm crop everyone expects.

The 8 sided would need to keep the 24mmx36mm in both landscape and portrait crops. This would leave a 17mm square between sensors on the wafer as waste. But this would offer the most flexibility without thinking of round sensors. This would be a cool sensor shape.