I avoid using data outside of connecting to wi-fi, but I prefer smaller phones. The increase in size of screen just isn't worth the extra burden it causes. Not to knock the newer and bigger models, the Iphone 6 looks great, it's just a matter of comfort for me.
I prefer large phones. I have been using the Galaxy Note since the 2 came out. I'm upgrading to the 5 next month. The reason I choose bigger phones is because I use it for my ebooks in class, I have big hands for a girl so I need bigger buttons, and the screen display is awesome. I wear glasses so if I don't have them, I am still able to see my phone activities good.