I would recommend Waterloo as well and the reason is BECAUSE they have a tower. The airport is not really that busy and you get experience with radio procedures as an everyday occurance. The practice area is right outside the control zone so there's not a lot of wasted time transiting. I would not recommend any airport in the YYZ control area
I would also suggest you interview the instructor rather than the other way around. Try and get an instructor that does it full time so he/she is there every week. If your constantly changing instructors it can easily add 5-10 hrs on to the time spent getting your license. ( which comes out of your back pocket and into their cash registers)
On another topic, in my experience as an instructor from longgggggg ago, close to 90% of students get their license, fly a few close friends and family around and then never fly again. Be very clear in your mind as to why you are starting in the first place. The first question students ask is How much?..they then go home, wrap their heads around that amount and budget for it. What they don't realize is that the spending of mega $$$$ never ends when it comes to flying.
Good Luck.