I have a small firm and I have been using QuickBooks since 2012. I went into a lot of research for deciding as to who would be the best hosting provider for QuickBooks. Some were bad and some were good but in the end I rooted for AceCloudHosting. The main reason being that their pricing structure is fairly competitive and the way they treat their customer is very satisfying. Great tech support as well, all my issues and queries were promptly resolved.
There were some issues related to service interruption few days back..hope it wouldn’t happen again.