2017 is better in almost everyway
1) better cpu and gpu
2) better keyboard
3) proper 10-11hours
The keyboard in the 2017 Pros is the exact same second generation butterfly mechanism as the 2012. I think you are thinking about the MacBook, which likewise also received the second generation butterfly mechanism. The battery is also the exact same part as 2016, and the GPU is the same, just with a name change and tiny bit of an increase in clock speed. The CPU is the major upgrade.
Not saying the 2017 isn't better, because it is with the new processor, but just do not overstate the differences.