I have both the Kobo Glo and the Kindle Paperwhite.
Here is my assessment of my two units
The Kindle is much faster.
The Kobo Glo has dicey firmware and (sometimes) will produce a screen that is only 1/2 or 3/4 full of text.
The light on the Kobo Glo is brighter - but very manageable.
I like the Kindle firmware much better.
Moving from mobi to epub is nothing - I use calibre.
The Kindle paperwhite is a bit heavier than the Kobo Glo.
The Kobo Glo can use an mini-SD card.
I have no need for a mini-SD card.
I prefer both units, and enjoy both units - for the added luxury of having some variety in my life.
In case someone here is forgetful, the comments are based upon my experiences with my two units. Your life-force may vary.