DANK Market

It is a fantastic app, with a great performance in the website (loads fast and looks great), and a seamless, easy to use settings panel. They have done a great work in making something complex (setting up options with or without conditional logic) very easy to use.

We've used this app for two sites, one that sells food and other that sells household products. It works great in both. You can set up any product option you want. Highly recommendable.