I'd go for a shelter cat. Very few are purebreed Maine Coons but some are full or half if you're particular.
Maine Coons have lovely reputations but each cat is an individual. Mine are half Maine Coon and they have been the best shelter cats I ever had. I went by their personality and their big purrs, not by knowing what they were before handling and choosing them already. They grew up to be all very different from each other (I adopted 3 from one litter). One was a gentle giant, another is wild and sometimes neurotic but intensely affectionate (and sometimes bites hard for no real reason), another is incredibly gentle unassuming and sweeter than any cat I've ever known. All give good eye contact, but I have not seen that in all Maine Coons I have met since. It's because I gave THEM the parenting they needed to be secure.
They do have some built-in health conditions when they age but they are generally healthier than most purebreeds. Be prepared to clean up a lot of hairballs, even with brushing and hairball treats, with any long-haired cat. Don't expect all jumbo-sized cats to be lap cats, ever--or even like to be carried. What you actually want in a cat may not match a particular breed's predispositions.