Besides price, condition, mileage, remaining warranty, etc., there is only ONE scenario that I can think of where the features of a 2019 SE outweigh a 2017 SEL, and that scenario is:
The 2019 SE has the optional driver's assistance package (blind spot monitor and adaptive cruise control) while the 2017 SEL also had those features optional. You can easily tell if the 2017 SEL has it by checking if it has digital gauge cluster. If the 2017 SEL has the digital cluster, it has all the safety features of the 2019 SE and then some. For the 2019 SE, you'd have to check the side view mirrors to see if it has blind spot monitoring.
2019 e-Golf SE, Pure White w/ DAP and deAutoLED H7RC HID's
2016 e-Golf SE, Pure White w/ Ed's Golf R Replica HID's (SOLD)