Wow, that's a multifaceted question. Some dogs don't even like toys while others may obsess over them and everything in between. One thing is for sure. Make sure whatever toy you get for your dog is tough enough that they can't tear it up and ingest parts of it. Many dog toys are made from indigestible or toxic materials if swallowed. Our veterinarian has plenty of stories and x-rays to demonstrate this.
Our morkie is small and he loves squeaky toys. He's nuts about them and plots to interrupt our phone calls and conversations by squeaking them as loud and as fast as possible when we're on the phone or visiting with friends. He'll play all alone and entertain himself for quite a long time without any prompting but he gets into it even more if you ask him 'where's your fish Jo' or 'get the chicken'. He has about 10 different ones and knows which is which. Roxi and Rambo both play with toys but only if we play too. And their attention span is short. But the fun part comes if we get them wound up and then tell them to get each other. Roxi the world's most gentle Rat Terrier and Rambo, the world's toughest Maltese never hurt each other but their antics and growling are a ton of fun to watch.