I think the main one that comes to mind is Gintama, not for any content reasons or reservation about whether or not I'll actually enjoy it (I think I probably will!) but for a much simpler reason: length. It's a struggle for me to really commit to a long-form series and anything over 100 episodes gives me pause because I realize I'll have to invest in it for a while to get payoff and that either I'll slow my progress even more by juggling it with other series or I'll have to accept that I'll spend this big chunk of time on one thing when I could finish a lot of other ones on my backlog, so it usually makes me procrastinate on starting at all. I might also add LotGH, but eventually in uni I did try it, watched like 20ish episodes and just didn't really care for it, and put it on indefinite hold ever since but I at least picked that up so that's better than most! I do intend to go back and finish it sooner or later though since I know that's one where the real payoff comes later on in the story.

This is kind of a thing for a lot of VNs too, though to a lesser extent. I feel like a good chunk of VNs I'm really interested in (especially Key ones) are all at least 50 hours to finish and especially for the ones I've seen the adaptations for already it makes it harder to jump into. At least some of the super long VNs I really anticipated were things I knew I'd enjoy and eventually finished (Umineko) or can reasonably finish once I just sit down and focus on them for a good enough stretch of time (WA2), but those are usually some of my most hyped media ever so I can accept a good 70 (or in Umi's case like, 120-130 or whatever it was LMAO) hour read knowing I'll get greatness out of them. Really that's how it probably is for a lot of longer VNs too but yeah.....time is hard. It's so much easier to just binge a 5 volume manga or one cour anime than to sit down and go "alright, 80 hours to finish this one thing" and while some are shoe-in favorites for me, it's a huge bummer when I spend that much time on a VN only to give it like.....a 6. Like that's not a bad score but if I knew all that time would end up just like that, I'd probably have preferred to pick up random seasonal A that's 12 episodes long and I also would've given a 6, it's just that sorta thing.