The advantage of Parkside is it would be less costly, although with TTC insistence on tunneling (i.e. Vaughan), I am not sure it would be a huge savings. Also, I don't know if its a selling feature that no station is needed between Queen and Bloor. A Keele interchange is likely easier than most in the west as well. Going up Keele allows several options, including Keele at the way, switch to Jane, or go to Rexdale.
Dufferin does have the density though. My imaginary Scarborough to Exhibition line would serve King West allowing the DRL to curve north sooner.
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