It depends very much how you use the processor as to which will be lower power.
For full details compare the "supply current characteristics" parts of the data sheets.
For example, stm32L053 running at 65 kHz will consume typically 36.5 uA but worst-case (at extreme temperature) is guaranteed to be less than 110 uA. (Sorry I didn't see which stm32L0 are L0+)
In comparison, stm32G070 running slower at 32 kHz seems to have a lower typical current of 19 uA but worst-case is much higher at 570 uA.
And if you want to guarantee (say) 1 year battery life, then the worst-case figure is the one you should use in your power-budget.
If you're using a different clock frequency, or if the processor spends a significant portion of its time sleeping, then the comparison will be different.
I think that in general, a more modern processor will have lower active current consumption. But if the processor spends most of its time idle / asleep, one intended for low-power operation should consume less power as its semiconductor process is likely to be optimised for low leakage current.
It isn't an easy thing to work out. For example a processor that can complete its operations more quickly (perhaps by running at a faster clock or using hardware-assistance for key calculations) and so spend a much smaller portion of its time awake might overall have lower power consumption.
Hope this helps,
Danish
