Bigger isn't better.
I had the big Samsung phone, and after the screen broke, I felt that it was too big.
I have a Xperia active now because I like the water resistance of it and tougher screen, battery life is a bit small, but ok if you're not gps recording activities for more than 4-5 hours per day.
The smaller screen is fine, mostly because for any real information gathering I use my Ipad.
I'd recommend to restrict to only what you really need for your phone, and then let a tablet work for the rest of your mobile IT needs.