As it says above - I've used Sage50 for nearly a year and my accountants club membership is up for renewal soon. I'm thinking of moving to Quickbooks Premier for the simple reasons that it seems (on the face of it) to be able to do everything Sage can at a fraction of the price. Also QB tell me that remote access functionality is built in which is a major plus over Sage. I know Sage and it's capabilities pretty well having run two businesses on it in the past (as FD) but have never used QB.
So, what are the pros and cons?