That's an interesting question! It's gotta be the higher hills of Broadview/Haller Lake, right on the border with Shoreline. I'd be surprised if the average winter isn't above 10" there. You've got the elevation, it's basically right under the southern edge of the typical PSCZ, and the UHI is a little bit weaker there too.That hill in Maple Leaf is probably decent too.
Really anywhere north of 50th is going to see dramatically more snow than the rest of the city in a typical year. That said, I've also seen the top of even Capitol Hill get 6", while there's literally nothing on the ground by the time you get down to I-5 and downtown. Crazy what a difference a few hundred feet elevation can make when most storms are so borderline here.