Dogs are very adaptable, depending upon their breed, but typically, they are pack animals and like to be in a pack. First and foremost, YOU are their pack and pack leader so if they have your attention, that will keep them satisfied.
But I've found that most dogs do enjoy the company of other dogs, especially if their owner must leave them for a good portion of the day. It isn't healthy for a dog to be alone without social stimulation for long stretches on a regular basis just as it is for humans.
Our beloved border collie was loyal and loving as an only dog but he sure thrived with the company of another dog. He was never alone when we were gone and benefited from the mental and physical stimulation that only another dog could give him.
Our three chis sure love their lives.
Yet even though they love each other's company, they really prefer to have our attention and affection first. It's like having three little kids in the house all over again. I guess they provide mental, physical and emotional stimulation for us in return.