Personally, my single biggest bug bear with the TTC is their atrocious line management. On paper, many services that the TTC runs should be very good, but the issues with line management must run deep in the institutional blood, because it's been on going for decades - surely there must have been some personnel turn over in the last 20 years - and I haven't seen it in such a large capacity in any other city I've been to. Prague's trams (apart from not being slowed down by ridiculous safety rules like they are here) run in a mix of private ROWs, mixed traffic, and pedestrian only zones, and I've never experienced anything like this there.
Also would like to see:
-better communication vis a vis delays
-all door boarding, everywhere, at all times
-for the drivers to be taught finally that they're not the stars of John Wick and to stop yelling at transit photographers