Too many variables to answer simply:
In terms of resale, "popular" 1 bedroom sizes are approximately 500-650sq.ft. "Popular" 1+1 sizes are 600-700sq.ft. "Popular" 2 bedrooms start from 750sq.ft.
That's not to say there isn't some crossover. We've seen 900sq.ft. 1 bedroom units priced at $500,000 and we've seen 600sq.ft. 2 bedrooms priced at $300,000. "Most" buyers with a budget of $500,000 would probably expect 2 bedrooms in a "standard condo" (not including luxury product here) - so as you said, it would probably take longer to find a buyer.
In terms of appreciation rates, we've studied a LOT of different buildings across Toronto, and 2 bedroom units tend to appreciate 1%-1.5% slower than 1 bedroom units.
HOWEVER, note the following:
a) Two bedroom units are typically priced higher, therefore despite having a smaller percentage increase, it has a larger dollar value increase
b) My numbers also assume 2 bedrooms are larger than 1 bedrooms (and thus, more expensive). I have no data to back up what appreciates more when the 1 bedroom and the 2 bedroom are the same size and price.
So to answer your question in a very roundabout way: The "popular" choice is to go with the 2 bedroom in that price point.