The fundamental disagreement here is the degree to which Y/Bloor needs relieving and to what extent that should be prioritized over promoting ridership growth. Alignments and station spacing can only be agreed upon if there is consensus over how relief of Y/Bloor should be prioritized. The status quo opinion seems to be that relief of Y/Bloor is the foremost concern. To that extent, I would agree that a rail corridor alignment with few intermediate stops would be the best option. Contrarily, ridership growth would best be served by dense station spacing through existing urban neighborhoods which lack quality transit.
Maybe I haven't been clear on this, but it is my opinion that relief should not be prioritized over transit expansion and improvement.
Financially, relief would not benefit the TTC. A line focused on relief would by design have few intermediate stations. The majority of such a line's ridership would be transfers to/from the Bloor line en route to downtown and the vast majority of these already exist. From the TTC's perspective, the system would carry roughly the same amount of people as the present over more subway and would have paid a few billion dollars to do so. It may sound wrong to prioritize the TTC's finances over the comfort of Y/Bloor users, but there is no free lunch. The capital costs would simply come out of other project and the deteriorating operating performance would suck money from, say, the streetcars or suburban feeder routes.
Performance wise, a relief line is suboptimal. Crowding at Y/Bloor is very time sensitive and concentrated in the peak hours. The issue isn't crowding, but time specific crowding. If we build an express bypass the tunnels and stations will exist every hour of the day in every direction. You are paying for 168 hours a week of relief when you really only need maybe 20, and more to the point would only need it in the prevailing direction (a DRL in the AM would relieve westbound Bloor passengers headed to Union, 1/8 of the total trip combos possible that would interchange at Y/Bloor, not including through trips). So it is a very inefficient proposal because it doesn't consider the timing of crowding nor orientation. The solution? Subsidized express buses to parallel Yonge (Avenue, Bayview, Mt. Pleasant), taking out subway seats for rush hour, hire people to literally push people to the ends of the platforms, create boarding cues (like at wonderland) and get downtown governments to try to schedule around rush hour. If all else fails, charge a rush hour premium. The key is creating solutions that can be scaled to demand.
Meanwhile it is no secret that transport downtown is not what it could be. Without trying to go out of my way to bash streetcars, it is self evident they are not reliable means of rapid transit for reasons that are implicit to their design. So, it is my view, that the priority has to be improved transit downtown as opposed to relief schemes. I don't feel confident asserting definitely which route would best improve transit. Front or King could well provide this better than Adelaide or Richmond, I care more about the goal than the means. The rail corridor option seems misleading. Though its premise is lower costs by using existing ROWs, this has probably been overstated. We are only talking about mile and change where the rail corridor would be available (Don River to St. Lawrence Market), all of which will be only ~250m north of the WELRT and 500m south of King.