Rainforest
Senior Member
More to the point, an extension eastwards from McCowan only makes sense on Ellesmere,
Depends on the design; I would consider either Ellesmere or the 401 corridor. The 401 option is probably cheaper, and will run faster due to having fewer stops. While the Ellesmere option would do some local service, in addition to the main goal of connecting to Lakeshore GO.
Either way, probably not Sheppard, as Sheppard has no density east of McCowan.