I'll start off by proposing my alternative to Transit City. At $10 billion, we could have got nearly 33 km worth of subways. So I would propose the following:
1) Sheppard East subway extension to Scarborough Town Centre - 8.6 km
2) Bloor-Danforth Extension via Eglinton-Danforth - 5.8 km
3) Bloor-Danforth Extension to Sherway Gardens - 5.3 km
4) Sheppard West subway extension to Downsview - 4.4 km
5) Replace proposed SRT extension to Malvern with Transit City style (at-grade, centre of the street ROW) LRT on Progress and the Hydro corridor north of Sheppard). - 5.5 km of LRT = 1.1 km of subway equivalent costs. (Use much of the current SRT infrastructure like the yard).
This would all be on top of the current subway extensions to the Yonge and Spadina lines (after Steeles the province and York Region are picking up the tab anyway). If Mississauga was willing to chip in its fair share, the western extension of the Bloor-Danforth line could be extended to MCC. The remaining money (8.1 km of subway equivalent or 2.44 billion dollars) I would use to deploy curbside bus lanes in various places (some approximating current TC lines like and Sheppard East past Midland and some new ones like Ellesmere). Where affordable and justifiable I would consider LRT like Finch West or Eglinton West for example.
Beyond that if more money were to come along, the priority for me would be an Eglinton subway from the airport to Markham Road and build the DRL. I would save the construction of the bulk of the LRT network for the the third phase and it would include various projects: Progress LRT to Malvern via Centennial, Finch (East and West) LRT, Steeles (East and West), Ellesmere LRT from STC to UTSC, McCowan North, Kennedy Rd or Vic Park, Waterfront West and East, Jane or Bathurst,etc....I am not that great on the west end and there's a few parts of the city I don't know so there's obviously some places that I may have left out that would deserve LRT or BRT. Basically the point is I would have said LRT construction until I had finished a significant portion of the subway network.