Ok so I have tried researching all of my options but am quite confused and need some help. I am currently an Aeroplan member and qualified for Elite35 for next year. I am however annoyed at Aeroplan for changing the program and am very dissapointed in what is now offered. Not to mention it is a little enticing that US carrier programs offer unlimited upgrades while with Aeroplan I get to upgrade maybe 5 times max with my 30 credits.

My travel will be changing drastically next year and I would just like some frequent flyer opinions on which program I should join. I currenlty have approx 135k points with Aeroplan but will start collecting with a new program in the New Year. Here are my new travel details for 2013.

Main Departure Hub: YYZ
Destinations: Mainly Canada, USA, Mexico with possibly 1 oversees or SA trip. 70% will be between YYZ to varied US destinations. 20% between US to US destinations. 10% Mexico
Flight segments per month: Min of 5 segments per month not counting any possible connecting flights where I would pick up more segments.
Current main points card: AMEX Coprorate with membership rewards (have usually transferred to Aeroplan)

I am thinking United Mileage Plus would be best because of possible accumulation and ease of using other star alliance partners to collect SQM and miles but would love any other thoughts. thanks so much!