Help me choose my next phone! (Note 2, S3, iPhone 5, Nexus 4)

I am currently looking for my next phone and feel completely spoilt for choice so am asking for your help to decide! I have the following four phones in mind:

1. Galaxy Note 2

2. Galaxy S3

3. iPhone 5

4. Nexus 4

I have played with all of these phones at some point (mainly in shops) and have to say all four have their good points so I need some advice. Is the S Pen as useful as it looks? I've spent a while with this and it does seem very intuitive and is it worth the extra cash over the S3? Is the app store that much better than Google Play? (last time I used it was a couple of years ago when I had the original iPad). Is the Nexus 4 even worth looking at not purchasing through Google Play due to stock levels?

I will be getting one of these SIM free as I don't like being tied down to a contract and would like to know which one you would choose...

Thanks for the help in advance!