Chihuahuas are as good as they are handled to be. Just like Rotties, Pitties, and any other breed.
The breed differences have a lot to do with energy, focus, pray drive etc. Oh and hair, or more like how much you want to deal with dog hair. I love big fluffy haired northern breed dogs, but I don't ever want to deal with that much dog hair again. Same with labs. I love my working class dogs they are so good at being focused on what ever.
My issues with Chihuahuas is their size, They are know as Eagle and Owl and Coyote food around here. If you plan on being out in the wilds that may be something to think about.
My dog is huge, something I may rethink for the next one. Even so, he is not allowed out after dark on his own here.