I lived on Yonge between Shepp and Finch for a year, and Bayview Village for a year. Yonge street has newer condos, places to walk to. My wife and I both in our 20s found ourselves wanting to go back to yonge street for some fun when we were at bayview/shepp. If you like eating out, karyoke, go for walks with lots of ppl around but not as "downtowny" as yonge/egg, go for yonge/shepp or up to yonge/finch. Yonge and 401 doesn't feel like part of the community as it is in its own pocket away from everything.
Bayview village while cheaper, has some benefits. Yes, bayview village is expensive and "uppity", but there is a loblaws, lcbo, shoppers, med/dental offices there. Also there is a YMCA walking distance from NYC condos, which just so happens to be right by the subway entrance, and 401 exit!
I have a feeling that this location will grow A LOT in next few years, as concord is building 12+ condos where cdn tire is. The area behind bayview village has some parks and makes for quiet walks.
If you want more action go for yonge/shepp or more north....same accessibility, less action, less shops, quieter go for bayview.