None, took me a lot of time and effort to source an AGM battery from an unfamiliar shop only to have it fail in about 3 years.
Chris @ Eunos Custom Automotive is your best bet, I have him do almost everything in my car, and I am sure a few people on the forum can vouch for him.
Cannot tell you about my new battery, only had it for about a month.
btw, feel free to visit Vancouver Miatas
http://van-mx5.chronosdigital.com/forum/