So, I’ve owned cycleops hub power meters, multiple generations of quark/sram crank power meters, and pedal based power meters from Look, Wahoo, and Garmin.

The Looks were total crap. All the others worked fine, and served their purpose for me. The pedal based meters were the only option for tandems. The Garmin Ralley work for off-road, and the Wahoo’s allow me to use the speed play type pedal I prefer.

Some of them were true two sided, measuring power from 2 sensors, some gave 2 sided power extrapolated from a single sensor, and some were one sided.

For me, my L/R power is close enough that 2 sided vs 1 sided just wasn’t meaningful. One thing to ask is whether any power discrepancies left to right are within the margin of error of the pm.

Personally, I would pick a power meter based on my budget, and how I intended to use it, without worrying about about crank vs pedal, or one sided vs 2.