Imo iPhone 5S any day.
Sure if you want to support the open source movement Z30 could be the way to go, but the thing is, is there anything to support in couple of months?

Personally looking to getting iPhone 5S or next gen Lumia next to Jolla. For some reason I have urge for iPhone. Haven't had one since iPhone 4. Wanting small no nonsense phone that just does it thing I guess.

520 as 100 euro phone is what it is, but Lumia 800/900 was crappy camera phone. Lumia 920 especially with the new updates is very nice, maybe even slightly better than 925 that has slight hardware advantage on camera.
Though the next gen Lumias look to be much better, as long as you don't count Lumia 1020 that's it's own thing, like 808 PureView.