WPF advantages
- It's newer and thereby more in tune with current standards
- Microsoft is using it for a lot of new applications, e.g. Visual Studio
- It's more flexible, so you can do more things without having to write or buy new controls
- When you do need to use 3rd party controls, the developers of these controls will likely be more focused on WPF because it's newer
- XAML makes it easy to create and edit your GUI, and allows the work to be split between a designer (XAML) and a programmer (C#, VB.NET etc.)
- Databinding, which allows you to get a more clean separation of data and layout
- Uses hardware acceleration for drawing the GUI, for better performance
- It allows you to make user interfaces for both Windows applications and web applications (Silverlight/XBAP)
WinForms advantages
- It's older and thereby more tried and tested
- There are already a lot of 3rd party controls that you can buy or get for free
- The designer in Visual Studio is still, as of writing, better for WinForms than for WPF, where you will have to do more of the work yourself with WPF
Thanks
Koolprasd2003
Editor, DotNetSpider MVM
Microsoft MVP 2014 [ASP.NET/IIS]