First, congratulations on getting your two acceptances! That is excellent, although you have to make this decision and it is tough, it is good to be in. Either way, in September you will be on the path to pursuing a law degree. Here is my two cents, take of it what you will.
1) Based on what I've read on this forum and experienced over the past few years (as a hopeful applicant and filing assistant in two family law firms), it is all about connections. If you go outside of the province or out of the area for Law School if you have connections/networks with lawyers in your desired area that would be beneficial. You would have to commit to staying in contact with them and pursuing experience in Ontario/GTA to be competitive once you have finished law school. In terms of proximity to the GTA, both are far, even though Lakehead is in Ontario it does not necessarily geographically give you an advantage.
There are definitely advantages to going to certain law schools based on reputation, but I think with planning, determination,and hard work you can overcome those hurdles with the right opportunity, interview, or placement. Given that, I would suggest you look at the program, law specialties, and location/lifestyle for each program.Think about the 3 year law experience that you would like to pursue. I think based on what you have stated Lakehead may seem like a better fit for the education portion. If things like; prestige, reputation, weather, community etc. are important to you that is where you would have to continue to weigh the pros and cons. My suggestion is to take a personal approach to making this decision, think about what you would like, your values, and goals.
Congratulations again on your acceptances.No matter what you decide, you will have the chance eventually to make it back to the GTA, so please put importance on you and what you would like for your law school experience. I do not think there is one clear answer that can be given. All the best!