EasyTask
I abandoned Things before its full release in January 2009. I had begun comparing it to EasyTask and switched to the latter. They are very similar in many ways (both use the GTD principle) and I couldn’t say that there was a major thing that EasyTask did better than Things. It was a bunch of little things.
1. I liked the visual style of EasyTask.
2. Whilst they both cost about $40, the iPhone app for EasyTask is free, whereas the Things app is $10.
3. EasyTask has the ability to sync between Macs via the cloud, as well as to the iPhone. It is possible that Things does this now as well, so check it out before you choose between these two programs.
I’m very happy with EasyTask. Like Things, you can fully configure your projects and categories, and sync to iCal. I use it at home and work without fault. The only complaint I have is to improve the presentation of which tasks are due. Whilst you can set both priorities and date deadlines and sort on both, sometimes items hide in one of the many categories and the only way to see a definitive ordered list is to select everything.
On just one occasion have I contacted the makers of EasyTask, when I had an issue syncing on the iPhone. They got back to me very quickly with the explanation, which turned out to be a slight difference in the sorting of items between the Mac and iPhone versions.
At the end of the day though, the choice between both these apps is personal preference. I would recommend either.