Wunderlist. Lightning fast sync across devices, a webapp that is indistinguishable from the local app, a free version is more than I could ask for, 4-5 features

Wunderlist. Lightning fast sync across devices, a webapp that is indistinguishable from the local app, a free version is more than I could ask for, 4-5 features that are neatly organized/appropriately available, and even the sound it makes when I check off a task gives me joy. There's more that I can't recall at the moment. For a simple little list application, it reminds me every time I use it that other software could be this good, too.