Nokia Lumia doesn’t seem to coming any sooner than mid-January next year.
As for the HTC 8S will come out towards late December and cost close to ~18000/- -->20000/-.
I have a XPERIA go and because I do not video-conference the front camera is not a necessity in my case.
Never used any smartphone for extended periods save my XPERIA so I cannot comment on how the others fare. Also, most smartphones heat up a fair bit when they are under constant load.
Hope this helps, Cheerio!