[Fritzer]

Just research and find a bare bones, secure Andriod OS. Or keep the OS on it that shipped with the phone. Copperhead OS anyone? Never update, ever. Nothing should really be limited by you doing this, unlike iOS. The battery shouldn't significantly deteriorate until about 2 years into normal usage of the phone. At that point just buy a new one for $50-$100 and replace it. Should be fine.

Never buy Apple products.

[SharpAndCunning]

This happened to me on a Galaxy S4. It was an older phone, but I loved it. I did an update, and almost immediately, the battery would drain 20% in an hour of not touching it. I bought a replacement battery, just the same.

I was pretty pissed. I ended up trying out an Iphone, which I didn't like, and sold it for a Galaxy S8+. I'll end up rooting the phone when battery life become a problem. I doubt I'll do anymore updates from here.