I'm running 165mm cranks on my gravel bike and 175mm on my road bike. I like them both for different reasons. On my gravel bike, I have lower gearing and the shorter cranks help reduce toe strike on technical terrain. Also since I ride that bike on rougher terrain, out of saddle riding isn't an option for traction reasons. On my road bike, the 175mm cranks are awesome for torquing on road climbs and even my flat sprints benefit from the torque. I'm almost tempted to pick up a set of Dura-Ace 180mm cranks for that additional 5mm!
On a side note jumping back and forth between crank sizes, has showed me how to optimize my pedaling techniques and it's not all about crank length. For example I move forward on my saddle when I plan to spin at high cadence, which then utilizes a different set of muscles for spinning. When I go for seated sprints, moving back on my saddle utilizes another set of muscles to lay down the pedal power, while adjusting my hand positions on the drop bars. The great thing is that I can apply the same techniques to both crank sizes. Also when not cycling, I have a better idea on what leg/upper body muscles to work on when I'm doing strength training.