Be responsible and neuter your pets. There will always be the risk of them coming across a female in heat, and even 1 accidental litter is too many.

Now, while they may never become agressive towards one another, they are still developing. Will you ever want them to interact with other dogs?

Also, If a bad habit, like marking territory, begins, there may be no stopping it. And even if you are lucky enough to keep them perfectly housebroken in your home, will they ever be in anyone else's home? or at the vet or groomer? Most of the un-neutered dogs come in to the grooming shop and pee everywhere. Neutering would stop the behavior before it starts.

Neutering reduces the risk of cancer just like vaccinations reduce the risk of other diseases.

So, what reasons do you have for NOT neutering?