Does the benchmark score relate to the laptops, or just to the processors? From what source are the benchmarks? Off the top of my head, if all you want to do is 'mundane' stuff, I'd say the faster processor might deliver you better performance than the separate graphics card in the Sony. Either one should be a pretty quick machine, though.
Sony Xperia Z5 review: Hands-on with the phone which the Z3+ should have been