I'm not sure if the latest Mediatek, Exynos and Apple A7 processors are as good as the Snapdragon 801 or 800. Maybe someone else can answer that question.
Just wait for intels new mobile processors. They will blow these chipc out of the water with less power use. Unfortunately I see it taking a while to adopt as most makes will probably opt for the cheaper current chips to save money.
Isn't Tegra equal to Snapdragon ? I follow nVidia as I know there desktop line of GPU very well ! Mediatek is a processor for budget CPU, although they claim is crushes snapdragon 801. Octocore smart phone have the same similar roadmap as desktop counter parts, except nVidia can make the processors as they are smaller and less heat, heat always being an issue.
There are no phones yet with K1, just done 3 tablets thing Android. The latest Mediatek SoC, when coded for properly, is faster than the Snapdragon 805. Otherwise, the 805 should come ahead.