I would have to agree that the personal picadillos (sp?) each of us brings to the software choice probably silently dominates the decision. I've tried at least 5 of the Windows-based programs, and looked at Omnifocus on my son's Mac. Two things seem to influence my choice most powerfully. First, as David Allen notes in "Making It Work," most of the GTD software misses the mark because it is too complicated. I like Toodledo and tried it for a while, but it seems to be less intuitive than I want my GTD software to be. Second, I work in a team. Delegating actions is important. Toodledo has you click on the button in the corner to look at those actions delegated to someone else. I prefer to look at a project and see all actions together. If I want to see all the actions delegated to a team member, I want to have that option, as well. For review purposes, however, seeing the united view is critical for me. Whatever its flaws, Nozbe implements that feature wonderfully. I can easily invite team members to a project and (once they accept the invitation) review all of the actions associated with the project, no matter who is assigned to the task. For group reviews, that is really helpful. I can also look at the lists of actions assigned to any person when I need to just meet with them. FWIW, I also find Nozbe's interface simpler, which makes it easier to get buy in from others working with me. Unfortunately, I have a Windows-based system at work. So, Omnifocus is not an option. I do have an iPad, however, which some have described as a "gateway drug" to migrating to an Apple-based office. For now, though, Nozbe works very well, with its shortcomings posing no serious problems.