So this happened today:
Yup, I ditched my HTC One M8, which I liked in many respects. Android was a fun experiment, and is a smartphone detour I'm glad I took, but I always knew I would come back to iOS. My time in the desert is over and I'm back home.
More thoughts will be coming soon, but I should say I chose the regular old iPhone 6 in space grey (after flirting with the Plus model for a while). In the meantime, read Josh Ginter's review of the Plus at the newly-revamped Tools & Toys.