Leduc for all purposes is Edmonton.
We own a sizable building in StonyPlain since 2004 (almost ten years now - wow), and used to own two houses, now one, and it certainly is not Edmonton. Spruce Grove a wee bit closer than StonyPlain but is mentally and distance wise further away from Edmonton than Leduc, primarily due to airport and traffic south to Calgary.
Leduc/Nisku is a good market, as is Edmonton of course. Spruce Grove/StonyPlain is good too, but smaller and more volatile and as such prices and rents are lower by 10-15%.