Things you really like... but can't recommend
What it says on the tin. What is some media you really, really like... but due to whatever reason, you know you can probably never recommend to your friends and/or other people (for whatever reason).
For me, it is Legion of Superhero comics and the Dark Tower books. Both are massively huge works which require a lot of commitment to get through.
For the former, it's because... well, despite the fact that it's absolutely great and a complete series, to really appreciate it and understand it, you have to read a lot of Stephen King books outside of the Dark Tower stuff because a lot of concepts/characters are introduced in those non-Dark Tower books and quite frankly, that level of commitment is not exactly something you can reasonably expect from people.
The second is that while the setting/characters of Legion are really, really interesting and now a sadly underrated part of DC's canon... it's Post Crisis on Infinite Earths, it's continuity is an absolute mess that takes a lot of work to unravel (for instance during the 00s there were two contradictory Legion settings occurring at the same time) and also there is the constant threat of it being rebooted by the time you actually start to enjoy it.