For any reason?
I have several but a few come to mind. Olive Kitteridge is one. I bought this on Kindle in 2016 and I still haven't read it. I'm not entirely sure why I bought it because the premise doesn't particularly appeal to me and I don't tend to like books which are set in Maine but I've heard so many people say that they loved it that I really need to give it a go.
Jonathan Strange & Mr Norrell is another. It's such a brick and it's not really my genre but it does sound interesting.
Also too many classics to count. I've just rearranged my bookshelves to put all my classics at the front so perhaps that will help.
Which books have you been avoiding?