Kobo e-readers are quite decent. We have had the chance to test a few of them recently, and they are more than decent for those of you who just need an e-reader. All of these devices let you change spacing and margins but they are not perfect in this area. The user Metazoa at The-eBook.org has developed the Kobo Patcher to address spacing limitations of Kobo e-readers.
In order to take advantage of this Kobo patcher, you need to make sure your device has the right firmware installed. It seems folks have gotten the hack to work for Kobo Mini, Kobo Glo, and Kobo Aura HD. The instructions are available on The-eBook.org.[Source]