It is difficult to see this post using a n900!
Perhaps the full of pixels images make the reading hard to process.
Anyway, according to juiceme's measures the best option is raspi2 in battery duration. I wonder how different will be measuring with exactly the same kernel and OS on the three boards. Here were I live a raspi3 is sold in 35usd. Not raspi2 or raspi1 at least not found yet.
Where U got the sailfish OS ISO image for raspi?