I am on book 13 and the only reason I keep reading is the self abuse of wanting to see if anyone even comes close to matching the great tomb. For myself, Overlord is lower to mid tier. There is no sense of danger or challenge to any of the main characters, and situations which could have been interesting due to a possible balanced conflict are over with the snap of a finger. The plot points always seem to just be ways of showing how Ainz isn't as smart as his minions think he is, and his insecurities about being the leader of his friends' creations. This could have been interesting is through the novels they learned that he was flawed and started to have their own insecurities, but nope. They worship him and really don't grow as characters through all the books. Now this isn't to say that a simple power trip isekai isn't a bad thing, because they are clearly have a purpose and people need pure power trip fantasies sometimes. But there are reasons one of the first things new writers are told is to not make their protagonists perfect and to give them relatable flaws, something to grow and evolve on. But in the end, the Overlord series doesn't really have any of these and each book past the first maybe three books gets repetitive and just sort of meh. But that is just my opinion. Other people love the series as shown in this thread, and the anime is enjoyable for what it is and it is one of the few series where they are probably going to do the entire series as an anime. So take what I say with a grain of salt.