I could see significant differences myself in display quality, but that's just me. And there is a significant difference in battery life as reported in some of the threads discussing this topic, the gist of it being that the Plus has several hours more of battery life to it.
If you could not see a difference just get the one that you think feels good to use, to carry and will meet your day to day needs/usage pattern. It's such a personal subjective decision I can't really nudge you one way or the other.
I'm sticking to my Plus order for now because of the additional battery life and because my vision is wonky and the display looks best to me through progressive lenses. I also hope the larger display will serve me well for the GPS function in my car.
Drawback to the Plus is that I'm used to always having my phone with me in a pocket, usually. I'm going to have to figure out how to do that with the Plus. I'm not completely sure I won't end up with a 6 eventually. Though the 6 isn't really that much easier for me to carry, either. The 4s was the last phone I could easily pocket. The 5s is pushing it.