> Chrome is faster
Sometimes, but it depends. For example, Firefox beats Chrome at JSGameBench here (a gaming benchmark including canvas hardware acceleration and JS),
http://www.tomshardware.com/reviews/windows-7-chrome-20-fire...
Also, while Chrome wins on most standard JS benchmarks, real-world JS is different. New code often runs faster in Firefox than Chrome. For example, the Linux emulator in JS ran 2x faster in Firefox when it came out, and I can link you to bugs I've filed on Chrome where it currently runs code 10x-15x slower than Firefox.
> more light weight
Many browser shootouts find Chrome to use more memory than Firefox, especially with large amounts of tabs. For example, Firefox beat Chrome at both memory benchmarks here
http://lifehacker.com/5917714/browser-speed-tests-chrome-19-...
> more standards compliant
Definitely not so. First, while Chrome has various standards implemented first, so does Firefox (a few examples off the top of my head: anisotropic filtering in WebGL, Mouselock, various JS ES6 features like WeakMaps, etc.).
Also, Chrome ships with a lot of non-standards-compliant technologies that are enabled by default. For example, WebSQL, NaCl, Flash.
> It's also open source
Chromium is, Chrome is not. Chrome contains a lot of additional closed source code, from a PDF reader to a software shader engine.
Bottom line, there are plenty of good reasons to use either Chrome or Firefox. What is important is both drive each other to do better.