Right now I think wow is a much better game. But I could never bring myself to resub or buy cata. I've done it all. Not saying that I've beat every boss or anything, but I've been chain healing and earth shielding for years, no thanks.
I feel the same. I don't care how much I spent for my car, how many miles I put on it, how reliable it was to me, or how awesome it was.....I eventually just grow bored of it and want something else.
I enjoyed my time in WoW but that was then and this is now and there will be something else tomorrow.