I know this isn't a 'replacement' WebBrowser control, but I was having some awful rendering issues whilst showing a page that was using BootStrap 3+ for layout etc, and then I found a post that suggested I use the following. Apparently, it's specific to IE and tells it to use the latest variation found on the client machine for rendering (so it won't use IE7, which I believe is the default).
So just put:
<meta http-equiv="X-UA-Compatible" content="IE=Edge" />
somewhere in the head part of your document.
Obviously, if it's not your document, this won't help - though I personally consider it to be a security hole if you're reading pages not created by yourself through the WebBrowser control - why not just use a web browser!