Thru Hike Carry-on Backpack: Rei Trail 40 vs Ula Camino

I am planning on a week thru hike and am looking for the best hiking backpack eligible for carry-on. After some research, I've come down to two backpacks and wanted to hear honest opinion and experience about these two packs.

• Rei Trail 40
• Ula Camino

Thank you!