Need Help choosing a dog breed?

Okay, so im STILL looking for a puppy..I have a few dogs in mind, but im just so unsure about all of them. I've been doing research the last month or so and I would like to know what everyone thinks about these breeds. all opinions, answers, or advice is allowed, even if you dislike, love, or are neutral to the breeds listed, feel free to express those feelings..Ok, so first, is a Caucasian Ovcharka..They're simply mive dogs, very strong, very loyal and protective, but can be a very vicious and aggressive dog if not socialized right..Second, is a Cane Corso, this is a breed somewhat like a Pit I guess, also very strong, they're around 24 and a half to 26 inch's tall, they are even tempered, but are considered "Man Stopping Dogs"...Third is gonna be a Great Dane, they are the "gentle giants" of dogs, they can stand 30+ inch's tall very easily, and are very kind and loving, but not all that great of a guard dog..Fourth, a Tibetan Mastiff, like any mastiff they are very large stocky, powerful dogs, they are also even tempered but at the same time can be very good guard dogs in any case. And last but not leats, the French Mastiff, also know as Dogue De Bordeaux, these are generally shorter, stocky dogs, where the Tibetan is taller. These dogs can easily reach above 200+ pounds and exceed 250 pounds in some cases, they have mive jaws and are among some of the most powerful breeds..Sorry this is so long, I just want to know what everyone things of these breeds. Thanks so much for taking the time to read all this and I hope somebody could give me some first hand expeirence and some good advice. Thanks!