thanks to all who have responded - I now realise I made a mistake in asking the way i did (it has the potential to degenerate into another 'fanboy discussion'). I wouldn't expect that to happen here but it wouldn't be the first time.
My struggle with the windows phone was that your brain wants to treat it like windows, the windows we love which is full of options and possibilities and third party tools, etc. But the windows phone is none of those things. it's even more restrictive than iOS, without the apps. So it's essentially the most restricted device imaginable. I stopped using it when the nexus 5 came out.
This seems to encapsulate the replies so far, but it's ultimately fairly inconclusive.
Reading between the lines here it seems that the user experience on WP is generally excellent. The dissatisfaction (?) seems to centre around a lack (?) of customising options, and the fact that some (many?) of the applications available under other platforms aren't available under WP (is that a reasonable expectation?).
That said, WP seems to offer some options that the others don't?
FWIW the 2 handsets I'm considering are the LG G3 and the Lumia 830. I don't have any particular dependency or affinity with android, nor do I have anything of importance that I might lose (that I know of
). I'm not terribly interested in customising nor do I have any particular expectations of the hardware, so long as it works well and is reliable.
In the end this may come down to the toss of a coin