Honestly, I don't know. I've tried to answer this thread for a couple of days now. I don't tend to be attracted to breeds with an obvious standout trait that I know I wouldn't enjoy. I guess Dobermans would be my exception to that... I could list a bunch of things as to why they're not a good fit for me (along with things I do like about them), and yet somehow I have two of them anyway lol.
But Leonbergers and St. Bernards come to mind. I love both of these breeds, but they're SO big. I don't know if I'd actually like living with a giant breed. Even Doberman size is too big for me sometimes. But on the other hand, it's usually the combination of size + high energy that gets on my nerves, and giant breeds usually aren't super energetic. But even without that, the drool (for St. Bernards) and the hair would be a lot to deal with. I groom my dogs so often and I can't imagine grooming a hairy giant breed (or even a short coated Saint) as often as I do my current dogs. I think I might try fostering a giant breed/dog one day just to see if I'd enjoy one or not. If I ever do go for one of those breeds, it'll be a very long time from now.