I think part of the problem is that when writing for humans, you need some human-relatable characters. In most works that include an AI, it’s gotta be at least recognizable as a person. That leads to a lot of “dorky human” characters. Or, perhaps, human-style intelligences that are different in certain ways, but still recognizably human. Such as GLaDOS from Portal, or Prime Intellect from “The Metamorphosis of Prime Intellect.” I assume what you’re looking for right now is truly alien intelligences. Thought processes not like our own.
Those are fascinating, but it’s very hard to include them as characters. The best treatments I’ve seen of genuinely non-human intelligences are nigh incomprehensible, and it makes for great horror writing. Such AIs are basically Lovecraftian gods – powerful, inscrutable, and not really characters. The aliens from Peter Watts’s “Blindsight” are my favorite example. Absolutely fascinating, and absolutely unrelatable even in principle. At the furthest extremity these sorts of intelligences are like The Thing Behind Area X in the Southern Reach Trilogy (altho I haven’t read the third book yet, so I may be wrong). Based on the first two books, it is hard to say that there is even a thought process there. Is The Thing sentient, or just a force of nature? Is it a babbling incoherent force at the center of all things? Another great example of this (taken from real life!) is Yudkowsky’s short “An Alien God”.
But if you’re going for a happy medium – an intelligence that is mind-warpingly alien, but still comprehensible, and able to interact with humans on human terms – than I think your best bets are Peter Watt’s “The Things” and Peter Hamilton’s “Pandora’s Star”. In both cases the Intelligence is an alien rather than a machine, but really, what’s the difference when it all comes down to it?