Having tried just about every ToDo app there is, my preferred app of choice is Nozbe. I like the fact that I can use it anywhere on any device and have written extensive reviews as such.

Nozbe, as a company, is also a great example of a group of developers who are using their business to do some good in the world. Their customer service flows out of a desire to serve the customer rather than simply acquire more users.

Their new desktop version for both Windows and Mac is very promising. I've been using an advanced version for several weeks and here are my reactions:

Very nice looking. Gone are the hard ines and sterile landscape and in are greens and beiges as well as more prominent input buttons. It feels like a Mac Lion app and even offers full screen mode.
Accordian expansion. Unlike the older versions of Nozbe, the new desktop app features a three panel expansion process that grows if a project needs it to, giving you the ability to add comments and other details.
Excellent pop-ups. When you are about to delete something, a nice and large pop-up prompts you to confirm whether or not you are serious. It just feels slick to me.
Color coding. You can now add various colors to your tasks- I haven't figured this out yet but it looks promising.

What I don't Like

If quick-keys and keyboard shortcuts are your thing, the current version of Nozbe desktop isn't quite there. I have no doubt however that they will finish the shine on the version that Apple eventually approves for the App Store but it's that final 1% that will make Nozbe yet another option for your productivity toolbox.

Here is a short video from Michael, Nozbe's founder about how the desktop app is coming along:

P.s. if you'd like to try Nozbe, consider using the "Tools I Use" link to Nozbe in the far right collumn of the page. TDS gets a small commission for everyone who tries out Nozbe through that link. Click here for the link.