I just bought an iPhone SE. It's not as small as the Jelly, but way more usable.
It runs latest ios 11 pretty well, has a decent camera, and > 1 day battery life for my usage.
I am figuring it will last at least 2 years, considering it has the same internals as an iPhone 6S.
If you're looking for a small phone, the SE nails it IMO.