Going into the phone shop in the next few days. Was going to get the Blackberry but they have had profit fall and there's talk the app store won't get many apps which set me back to maybe getting the Sony?

Which is best? Switching from Iphone 5.

I would widen the field to the galaxy s4 and htc one as well to be honest.

The Xperia z is a good phone but not without its issues.... Have a look at the relevant forums on xda developers.

Definitely, both have better screens than the Z and the S4 certainly has a better head-to-head camera, the One's camera is a little different which makes direct comparisons a little difficult.

If it's the water-proofing that has you considering the Z, then the S4 Active would be worth a look as well.