they will always be happy to see you, they will always want to give you affection, they will always want to play with you, they will always enjoy long walks with you, they will eat whatever food you don't want
oh and it has been shown that a woman will find a man wearing jeans,t-shirt and taking a leasurely stroll with a dog to be hugely attractive
(don't ask, i am not sure)
they offer so much but i suppose it is not for everyone