I've purchased from several different suppliers over the years. I really like Emergency Essentials, even though if something is out of stock it can often take months to receive it. But I like their variety, pricing, and purchasing options. That said, I haven't had any trouble with any supplier from whom I have purchased #10 cans.
You can get some good stuff through Costco, but it tends to be larger orders. I've gotten Thrive brand cans through them, and have no complaints.
Mountain House pricing seems to be pretty similar over all of the vendors. The vendors often all have MH sales around the same time, too.