So which one you're getting and why?
Major differences:
Screen:
The 6 Plus isn't just larger -- it has a higher resolution (1,920 x 1,080 vs. 1,334 x 750) and a higher pixel density (401 pixels per inch vs. 326 ppi).
Landscape mode:
The 6 Plus will be able to use special iPad-style landscape modes on some apps when the phone is held horizontally; the 6 will not.
Camera:
Though both devices are equipped with an 8-megapixel lens, only the larger iPhone 6 Plus has optical image stabilization -- which should help out any unsteady hand that's shooting an image or recording a video.
Battery:
In addition, the 6 Plus has a higher battery capacity, meaning you can expect to talk, watch movies, and surf the Web for a few hours longer.
Apple Store is down at the moment, getting ready for pre-order