I might be a little partial. But I would recommend a Perro De Presa Canario.

They are great dogs. They are very protective of the family and property. They are leery of strangers but will accept them if you do. They are very agile for large dogs. I once saw one on Purina Pet Challenge or whatever they call it. They had a dock diving competition. This presa won the contest 3 years straight. Some people do weight pull with them. Most people do some type of protection work with them. The love water. they love to work. But they are very affectionate companion dogs too. They love to get attention from its family. If you show dogs they can be shown with or without the ears cropped. One of the breeders I know from the UK her dogs ears are cropped. She ships them to the States to another kennel I know. He crops them and get them trained to earn their CGC and then ships them back. I understand that she has to have some papers with her at all times from a licensed vet stating that the ears were cropped in the US. I like the ears cropped, but I;ve seen some that look nice without them being cropped. i wouldn't crop them if we had to keep those papers with us at all times.