** This comparison has been updated! Please visit our 2015 update.
We are in the process of switching from an extremely basic system of invoicing and accounting to a slick, automated, cloud-based service. Hurray!
I would like to say we painstakingly researched a long list of contenders - and we did glance over quite a few - but we only seriously considered two - Freshbooks and Harvest - because they both integrate with TeamworkPM.
Except for project management features, which we really don't need, our criteria for comparing the two services was pretty fine-grained. And since we put in the effort, why not share? Hopefully this saves someone a bit of trouble.