Advice on buying an Android Phone (Coming from Windows Phone)

Hi all,

I currently have a Lumia 710 (WP7) and while I really like it, it's time to get a new phone. I really like a lot of things about WP and I'm tempted by the camera on the Lumia 1020, but I also see the limitations of Windows Phone.

I'm leaning towards getting an Android phone this time around because I like the increased number of apps the customization options. It feels like Android widgets can serve the same purpose for me as Windows Phone live tiles.

However, I've been looking at Android phones for a while and I can't seem to make a decision. What's the best Android phone camera? The reason the Lumia 1020 interests me is primarily for the camera, so a good camera is important to me. I've been thinking about the Xperia Z1, but the reviews I've read seem mixed. Does it take good photos in low-light? I like the dedicated camera button on WP phones and it looks like the Xperia Z1 is one of the only major Android phones that has one, so that's a plus.

Also, how is the photo taking process on Android? Can you take photos without unlocking the phone?

Basically, I think I've narrowed my choices down to the Xperia Z1, the Galaxy S4 or the HTC One. Which one would you recommend for someone coming from Windows Phone? Or should I wait until the Nexus 5 is released?

Thanks!