its a conundrum. WebKit is a great engine, but nearly all good implementations are provided by Corps who's interests have very little to do with providing a good browser, and lots to do with what you do with that browser.
Firefox in turn might be one of the last major alternative Engines that is maintained by a company who's mission indeed is in a large parts to provide you with a good browser, but seems to progressively struggle to do so, while the engine is a good part of that problem aswell.
I find it harder and harder to deal with the many issues in daily usage -- and from a dev standpoint, FF is slowly surpassing Safari as the main blocker for being able to adopt new web frontend features.
I dearly hope Mozilla can get back on track. Accessing the open web shouldn't end up depending on a pick of Google, Microsoft or Apple.