@filipides: It really depends on what you want. If all you are going to do is put a couple of books on the device and read, it doesn't matter much which device you use. They all display the text reasonably well, you can page through it and read. They allow navigation via the ToC, highlighting, dictionary lookup, several fonts and sizes and some changes for margins and line spacing. Different people will tell you that different devices are better for one or more of these. But, it really comes down to personal preferences.
I posted my opinion of the differences a while ago in
https://www.mobileread.com/forums/sh....php?p=3678381. I don't think much has changed for the tolino. There have been improvements in Kobo firmware (the series list, some reading changes, dictionaries). The rest of the thread has some other comments. There is a much longer thread discussing the differences,
https://www.mobileread.com/forums/sh...d.php?t=324490, but, it did get distracted by a couple of arguments, so I'm not sure if it is worthwhile looking at.