Take a look at the LG G3, same size screen as the iPhone 6+ but in a much smaller form factor.This is my exact issue as well. I have an iPhone 5 now, and want to upgrade to a bigger screen. But the bezels on the iPhone 6+ are huge and seem like wasted space. However the screen size on the iPhone 6 just seems like too small of an upgrade.
My perfect phone size is probably the Droid Turbo. It has a 5.2 inch screen, but is only .2 inches taller than the iPhone 6. However, I'm on AT&T and really don't want to switch to Verizon.