Two main reasons: firstly, I really wanted to go to AFI at first because the model of constantly making films throughout the year makes you seasoned in just two years and of course, the prestige/name, but, THE COST makes it such a financial commitment that I'm not willing to make as a young filmmaker that may not earn so much in the first few years.
I had an awesome interview with Patty Meyer and Evan Schwartz at LMU, they made it clear that I would be a good fit and we kept in touch after. I also got a good scholarship on top of the tuition that's nowhere as pricey as AFI. The LA location is a plus and I can't stress how much I appreciate the three-year length. I've seen other people on this site post about how it helps you find your feet vs. the pressure of figuring it out in two years. The third year is mainly prepping you to be career-facing in addition to being artistic.
Vs. Chapman, LA location won over Orange County and LMU's aid package was bigger.
Vs. Boston (they actually gave me the biggest scholarship of all the schools), but the location just didn't make much sense to me and the alumni didn't give me much hope for networking either.
Hope this helps!