One said:
Android friends,
In your opinion, I'm coming from the iphone 5s. ...should I go 4.7" iPhone 6 or shoot straight for the 5.5" iPhone 6+?
As someone who switched from the iPhone 4 to the Note 3 (5.7"), I can't even tell you how much I prefer the bigger display. I personally would choose the 6+.
I got used to the feel in my pocket within about a day or two. You'll probably end up doing some more things with two hands as opposed to one, but I've never found that to be a bad thing, and I'm guessing it would be the case anyway when moving from the 5s to the 6.
Like others have said, when I pick up an iPhone now, it feels like a toy because of the smaller size, and I'd never want to go back to that kind of size. The overwhelming majority of people I know who have given the bigger size a chance for more than a day seem to have that same opinion.
Either way, you're going to have to get used to a bigger phone. I think you're more likely to later regret not going with the larger one than the other way around.
Good luck!