Been there, said that.
"My 5s does everything I need"
"The 6 Plus is too big"
"The 6 doesn't have enough ram"
Already having a Macbook Air, iPad Air and original iPad Mini I thought (all running latest appropriate OS) that my 5s would "do everything I need". I also thought, not even holding one, that the 6 Plus "would be too big."
WRONG!
I just upgraded a few days ago & am kicking myself for not doing it sooner. The issue is NOT that the 6 Plus is that big, it's that the 5s is too small. I'm using it "naked" and have no problems one handing it (calm down people) or concerned about it slipping out of my hand. It's the perfect functional size, maximizing the usefulness of all the things we're supposed to use a Smart Phone for.
Everyone says, "yea but now you don't use your MB Air, iPad Air or Mini do you"? Yes, of course I do - there are tasks & functions that are just more appropriate on those sized devices.
So, for what it's worth - don't listen to all the naysayers & doomers - UPGRADE already.