We use Simply Accounting in our (non-real estate) business, which we chose on the recommendation of a friend who is a Chartered Management Accountant. I've used it for the past 8 years. And our CA here in Calgary who takes care of our fiscal year end loves it that we use this program because it's the industry standard, and he and all of his assistants are very, very familiar with it.
BUT, if I had a chance to do it all over again, I'd choose Quick Books. Simply Accounting had a really steep learning curve. Everyone I talk to says QB is a breeze to learn and very intuitive. Not so with Simply Accounting. I still regularly spend time on their 1 800 line trying to figure out what has gone haywire, or to get help because I can't figure out how to do something. That being said, my bookkeeping background includes one course of Accounting 101 at a university level, and then years of experience actually keeping a set of books. I think if the person using Simply Accounting had more of an accounting background than I do, the learning curve would have felt far less onerous.
You should also know that once you choose a system, that's it. You are pretty well committed to it forever. They'll tell you you can port information over if you ever feel like switching, but when you really dig deep (as I did this fall when it came to renew with Simply), you end up losing years of data, and there are a lot of hazards switching systems. I don't recommend it, mainly because of the disruption to your business, and because if you need to dig into previous years of data (and I often do) it would mean operating more than one accounting program to get the reports needed. And that's just going to be a giant pain.
And lastly, consider the payment structure. Both companies (most annoyingly) just moved to a monthly subscription service. Because we are such a small business, I find this structure to be quite a rip-off. I want to own my software outright, and wait until the last possible moment to upgrade to next version - I want my cost per year to be as low as possible. I recommend calling both companies to find out what they can offer as a subscription service, or the option to buy the software outright. You should also know that what they initially offer you is a good deal more than what can be negotiated. I'm a long time customer, and I wanted to buy the software upgrade this past fall. It retails for over $800, but for me, oh valued and long-standing customer, now only $629. I balked, this was way to much. In the end, after days of negotiation, I paid just over $400, and am now good for at least 2 years. Anyway, I guess the moral of this story is: do your research. Once you choose your accounting software, you are pretty much married to it for the life of your business. Good luck!