Thanks for the informative replies guys. That Infrastructurist you quoted Wooster has a nice chart comparing cost/mile of various transit options as well, here
I think based on what I've read I'd rather see the city build a better BRT along Center St. To help with the permanence issue, really nice bus stops should be built - preferably on small parcels of land reserved for future subway stations. I'd even provide heating and security cameras. As well, the improvements Sir Humphrey mentioned. I could buy into the streetcar idea if the streetcar had it's own ROW at least from 16th Ave south into the downtown - people would equate that to LRT. If the current HOV lane with BRT actually gets you to downtown faster than a car going down Center, they should build on that strength.
Mid term, I would say commuter rail to downtown from Airdrie with a stop at a 96th Ave station to serve the far north + BRT connection to 96th.
Long term, A center street subway that ultimately connects to 96th avenue station for connections to HSR, Airport and the 'burbs. Initial subway staging would build in steps up Center as intensification warrants - with the 1st step across the river being the big dollar expensive push, to say 16th Ave as a 1st phase. There is a Safeway there that the city could partner with to build a parkade and free up the lot for a BRT interchange with a 1st stage subway into downtown. I'm sure the Safeway could see the benefits of being right beside a major transit interchange - I know I'd be using it if I was passing through. Considering they are talking 500mil for 8th Ave NW-South subway, I'd say just getting to 16th Ave is going to cost at least (guessing) $750 mil unless we are willing to put up with a long bridge over the east end of Prince's Island that gets us to a cut'n cover situation on Center sooner. It would be interesting to see a preliminary study of a deep tunnel vs bridge option over the Bow that takes into account the geology - without that the price really can't be nailed down to even within +/- 50%.