As was just mentioned, unless you are going to have them be registered show dogs, it is better to get them neutered, both for behavioral and for health issues.

1. It will eliminate the chance of them wanting to wander if they catch the whiff of a female in heat ... the biological urge to procreate can be strong, and I have heard many stories of dogs lost or hit by cars because of this.

2. It will, of course, drop the level of certain hormones which can sometimes lead to aggressive behavior as they age. This will not change their personalities, per se, but it will make that aggression less likely to pop up.

3. Unneutered dogs have a higher risk for some cancers.

It's just all around better for them to get neutered, and could save you some expense and heartbreak later down the road.

As my big brother would say "They may not think they are broken, but it's time for 'em to get 'fixed!'" They are a good age for it, they've done all the growth they need to in their bones, and so make that appointment!