At one time I would have said Lost. I watched the first episode when it originally aired and decided that I wasn't interested in devoting an hour a week to it to find out what was going on. I'd hear people talk about it as time went on, and so I had a vague notion of the show's structure. From time to time I would see bits of it on TV, and you couldn't help but see speculation about the show online and in the media. None of this inspired any interest in me to jump onto the show's bandwagon. Since I would be coming in late, I wouldn't know what had occurred before and wouldn't be able to see or appreciate how events and nuances in later episodes related to the past. There didn't seem any point to start watching.
Eventually, I read wiki information about everything that happened and starting watching the next to last season. I found the show interesting enough to keep watching it to find out what it all meant. By the end of the last season I was hooked on wanting to understand the show's mysteries. I was counting down the episodes to the finale. I didn't care how it ended I just wanted to know the answers. So after the finale I felt great relief, not because it fit any speculation or desire of mine, but because it was just over, and I could stop wondering. I also felt a lot of satisfaction, knowing that I had not wasted time watching all the prior seasons. As the last season showed, those seasons were just filler, and didn't explain or impact anything.
I think the show proved that audiences are willing to watch and enjoy shows that make them think and speculate, as long as they are well made and have interesting characters.
On the other hand, a popular show I will never appreciate and never stop loathing is The Bachelor. Don't get me started on that sick piece of crap. The premise is disgusting, to have a bunch of women fighting to gain one man's favor. It's dehumanizing and no one should watch it.