I will be sticking with Sony for the time being.
They are easy ereaders to use and coupled with Calibre, the organisational advantages totally overwhelm other ereaders such as the Kindle and Kobo.
To organise collections on my wife's Kindle keyboard requires an additional Calibre plug-in, more steps and more time.
My PRS-650 and PRS-T1 coupled with Calibre do this without any additional steps.
No contest for me.