Although, if you really want one that bad, get a Nexus 7 tablet with data, and run a VoIP number on it.
The N7 is easier to type on, and the one arcade game I play (emulator called Pinball Arcade) works so much better on the slightly larger device. So now I just play pinball a lot less.
VoIP isn't a real option. For instance, yesterday I had to reactivate one SIM at the airport, and could only do it by making a real phone call on the SIM. Google intentionally disabled this on the N7, and even people that hacked up the ROM couldn't get it working. And many times when I want a phone/SMS, for "emergencies", I don't want to hope my data is working well enough.
> with great batteries
A phablet with a big battery plus not-ultraHD screen would solve the abysmal battery life problems of modern phones... it's likely thinness suffers though?
The problem is that Huawei ships a terrible, messed up version of 4.3. Complete with a button to accidentally force close all programs (and boast about memory "freed"). And a shiny button bar, instead of just black. And bits of Engrish, which would otherwise be endearing, on the custom apps. It sucks. But if I could run Cyanogen on it, it'd be the best phone ever.
There's also the Blu Energy with a 5000mAh battery, but I don't know how good the phone is yet (it's only $150). Blu seems to ship mostly stock Android. The problem is they have many dozens of models (most under $200, a few around the $100 point), so it's hard to figure out what's what. They seem to be targeting Latam with cheap-but-nice devices, like Vivo Air. If they'd focus on a couple of top models, they could easily become the dev phone of choice. Not sure what the unlocking situation is.