I never spent more than 200 euros in a mobile phone (except for the nokia 6230 with a colossal 64Mb MMC and 0.3mp camera!)
At this price-point ,iPhone is not an option and android is really not impressing me, mainly for it's unconsistant performance and the fact that you must dedicate some time to get it run slightly faster.
I found myself ,with every Android device I had ,constantly pressing the task-killer to clean up some ram.
It started to become something like nightmare and I often found myself using futurephones to have less things to worry about in my mind!
But if money wasn't an object I would probably go for a pricier Lumia phone ,like the next 9xx
(if only the battery life would give you 1.5-2 days of moderate use) ..
I wouldn't buy an iPhone ,although I'm a sucker for fluidity and transparency ,mainly because I don't want another LCD screen like ever again
My next phone will be the Lumia 735 (or the next 7xx because I'm fed up with the SD400) mainly because of the great colors/ viewing angles of the screen.
All and all , WP is great on midrange phones and truly worrying free OS without any nasty surprices.