AWD on the Select adds 220 pounds. Here are the EPA ratings:
FWD 1.2L: 28 City 31 Hwy
FWD 1.3L: 30 City 32 Hwy
AWD 1.3L: 26 City 29 Hwy
The optional engine and 9-speed auto rather than CVT are compelling reasons all by themselves to get the AWD version. I have a 2019 Encore with the optional direct injection engine and 6-speed auto. It has about the same output as the 1.3L Encore GX engine. The AWD allows it to just go, not only in snow, but also on wet, muddy, or gravel roads. I'll never go back to FWD, even if I moved to the deep South. I live in Wooster, Ohio, so I have to put up with snow and hills, especially my driveway, which slopes down to the basement garage.
Here's a Truck King test of the Buick Encore GX where they compared acceleration on snow in both FWD & AWD. The difference is substantial: