I'd ignore the Aura and wait for the Glo HD instead (if its not already available for you), simply because the screen of the Aura isn't as good as it should be.
That apart, depends what you want from your ereader. If you aren't that fussed over having tons of control over how many fonts you can use, margin settings etc, and are happy with half a dozen settings as options, and want an ereader you can simply pick up and read happily on with no fiddling, then get the Paperwhite. If you'd like More control over how your books look (fonts, margains etc) then go for the Kobo as it has a ton of customisation options.
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