7. Android 4.1 Jelly Bean
With major performance improvements under its belt since late 2011, Android Ice Cream Sandwich had already done much of the heavy lifting for its delicious successor. But Android 4.1 Jelly Bean didn't disappoint, and it is the fastest and sleekest version yet. Speed improvements are seen throughout, including in switching orientation and recent apps, faster frame rates, and a more active role when adjusting processor speed for performance vs. power efficiency.