[p1necone]

Performance per watt is a pretty decent measure (and I would argue really the only measure that matters - assuming it's possible to get it "fast enough", and with the exception of IoT type stuff where you probably only care about getting power consumption as low as possible because pretty much any amount of processing power is enough).

You still need to somewhat segment into low/medium/high power chips when comparing them though as it's generally not possible to just take a very high perf/watt low power part and scale up the same design with the same level of efficiency.