This question gets asked a lot. And I have to say the answer is "No there are not other birds that can go with an African Grey." Even if you get a grey you need to be ready to house them separate cause there is not guarantee they well like each other.
When it comes to looking for a second bird you should get what appeals to you. This is not a pet for your grey it well be a bird for you to look after and spend time with.
After saying that I would suggest you get one about the same size. And inturduce them very slowly. (that is a topic for the training area)
I have heard of and read about parrots that were bought around the same time and only allowed out time together that got along great but as a bird gets older it is harder to get them to like new things. Just like with new toys and our Grey's.
So if you want a second bird get what appeals to you and if they happen to get along consider that a blessing but don't expect it.