Twelve hours a day is really too long for any dog to be alone. If you decide to purchase a dog, please think about having a dog walker come in during the day to take your dog out, taking your dog to doggy day care, or at the very least having two small dogs so that the dog will not feel so isolated.
A Frenchie is a good choice for your situation, but I am still concerned about that large block of time. If you are in the US I suggest you contact a French Bulldog breed rescue (check Google for a rescue that works in your city) and ask about a pair of calm adults that can handle your situation. You have to tell them that if the dogs do not work out you will need to give them back.