Changing from iOS to Android

Hi everyone,

I'm thinking about changing OSs. I currently have an iPhone 4S but as I'm moving to England in september I'm going to need to buy a new phone.

The last time I had a Android it was the Nexus One and it was really bad and I gave up on it really quickly but now it seems to be that the things I didn't like then are now more or less gone.

I'm looking for help in 2 ways:

1. Hardware - I have the entire summer to decide but currently this is the match up : HTC One (google version) vs. Nexus 4 vs. iPhone 5 (or the new one).

2. Software - I actually have iOS7 on my iPhone and even though it's really good I don't feel convinced, on the other hand, I know nothing really about Android (I did follow the Google I/O keynote but thats it). So can you tell me things I would like/hate about Android, anything I should know (I know that I'll be losing all my purchased apps).


ps. One more thing, if you recently changed from iOS to Android, I would love to hear what problems you had.