Do you even know what that
WebBrowser
[
^] control is? It is simply a wrapper for underground IE that is installed, in older systems or frameworks, it is precisely
IE 7.
To answer your question, "Which is better?"
The answer is simply, WPF. WPF provides much more flexibility, extension support and yes, the theme of each and every control can be edited. If you do not like the old theme, old control UI, you can change them all. Just edit their templates, that's it, you're done! WinForms doesn't support as much flexibility.
Now, if you want to create a web browser on top of IE, I won't say that it is a good idea. It is a very bad idea, because the WebBrowser control provides you with IE 7, as the engine. You can somehow create the web browser and add a few extensions and work out with some problems that may arise with the browser. That is pretty much easy and simple, have a look at my article:
Creating a custom Web Browser using .NET's WebBrowser Control[
^]
That said, if you want to build a "real browser", consider using some good rendering engines and build on top of them. The following links will help you in the process:
https://msdn.microsoft.com/en-us/library/system.windows.controls.webbrowser(v=vs.110).aspx[
^]
A better WPF-Browser-Control (IE-Wrapper)[
^]
C#: WebBrowser vs Gecko vs Awesomium vs OpenWebKitSharp: What To Choose And How to Use[
^]