I have almost completely migrated project management tasks to Basecamp, but if Gantt charts were important/needed for me (I used to generate them) I would go back to using http://www.omnigroup.com/products/omniplan/ it is OSX based, but has worked very well for me. There are a couple video tutorials on the site I suggest watching to get a feel for whether or not you'd enjoy using the software.

Good luck!