Given I don't have one ready makes me think I've been confirming my biases too much.

The most effective high level "argument" against bitcoin (compared to other cryptohs) that I've seen repeated over and over is relative developer activity. It's often presented without accurate data and taken as a given, but I'd like to see actual numbers. If we can convince people that more developers, or simply more really good developers, are building on bitcoin than elsewhere, it'll have a significant impact on the narrative.