What I'm looking for is updates and support for the operating system.
So which device would provide me with OS updates and upgrades for the fastest and longest duration?
And this topic isn't limited to smartphones. So feel free to reply with any device in mind.
Well, most will suggest the Galaxy/Nexus since many of the people prefer those devices over the iOS devices. I personally prefer the iOS because it's extremely convienent for myself and it fits my style. I'd recommend that you do your research on the pros and cons of each and find out what you want in your device.
Depends on the eco-system & how much flexibility you want.
If you want a phone that will "just work", iOS is for you.
If you want to customize & have a better screen, Android is for you.
If you choose Android, Nexus is the best "bang-per-buck" but Galaxy devices typically have better specs ... until the Nexus of that that year comes out.