On my 4 conveyances, I have
1) 165
2) 160
1) 155.

I ride recumbent, so it's a little different, on a bent your body is stuck and you can't push up and get relief (if that makes sense). So, short cranks are, I think, more important.
I'm 5'7" with a 32" inseam, so fairly long-legged.
I don't notice the difference between 170s and the 165 when I got them. When I got a bike with 160s on it - Wow! I began to spin in the 80s rather than 60s, I could go farther, climb better. My avg speed didn't change much, but I could ride farther.
My velomobile has the 155 (my choice was 170 or 155, and I wasn't going back to 170s)
The 155 really feel different, and I'm not sure I really like them. So, I'd choose 160s from now on if I can. I can spin nice and smooth and fast and I'm amazed at how easy it is to climb hills in the 65 lb velo - so maybe the short cranks have something to do with that.
I'm a huge fan of short cranks.