With Apple, you're truly screwed if they decide to stop supporting your phone. You can't do anything at that point. They also purposefully slow down your device with every new iOS release, and for no reason whatsoever.
With Android, you can just run a simple exe or a market app that roots your phone and gives you custom recovery, then you go nuts with any ROM you want. Pretty sure even a 5 year old Android phone can, through a custom ROM, smoothly run 4.3 just fine.
And don't say warranty blah blah; by the time they stop supporting your phone, your warranty is already done.
Apple purposefully makes iOS run slower on older devices by not bothering to optimize it whatsoever. Google always optimizes Android the best they can and, as a result, a Nexus One from many years back with a single core Snapdragon can and does run 4.3 beautifully.
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What are you talking about? No one is forcing you to do an update. It's your choice.
On Android there is no choice..