The 6’s relative mediocrity is probably why so many of us are looking around and trying the 6 Plus — which shares many of the same design flaws, but provides more substantial advantages. I’d still rather use an iPhone 6 than a non-iPhone, and the larger screen and better camera have spoiled me enough that I don’t want to go back to the 5S, but I don’t think anyone will look back fondly on the iPhone 6 in a few years. Ultimately, beyond any particular feature concerns or battery capacities, I hope the next iPhone doesn’t have as many physical design and usability flaws as the 6 series.
In the meantime, I might stick with the 6 Plus. It’s probably easier to buy pants with bigger pockets than to convince Apple that a bigger battery is a more welcome improvement on the next mid-sized iPhone than an extra millimeter of thinness.
Surprised at how many nerds I follow (see Marco's post for recent converts/curious) hadn't opted for the 6 Plus, I just assumed it was the default nerd option.