Hi Animal Guy.
I own a rottie and can tell you that there are huge differences between one and the other simply because they are still so popular. Our is great with kids (although I always advocate not leaving children and dogs of any breeds unsupervised), we have an 8 year old son, we meet other kids quite often and he is great with all of them. He is also the laziest dog we ever had.
Our dog is a rescue, and I would seriously suggest looking into rescues for the following reasons:
-reputable rescue group will assess the dog's temperament to ensure it will fit your circumstances and by getting a dog that isn't an 8 week old puppy it's easier to tell what the dog is all about, while with a little puppy it is hard to predict what it will turn out to be (infact, rotties that are human aggressive are in most cases euthanized by the rescue group or the shelter)
-reputable and ethical breeders are few and far between, it's hard to find them and once you do they may not have puppies for you
-it's much cheaper to get rescue, and if you are not a big fan of peeing and pooping indoor you probably won't regret it
-you save a life and it's a great thing to do, there are thousands of rotties available everywhere, so I am sure you will be able to find the right match
The drawbacks of rescue:
-well you usually won't know the pedigree and the past, but the truth is that even the puppy from the best breeder may develop health problems early in life, temperament wise, as I mentioned before, a reputable rescue group (and you should deal only with such a group) will do extensive research to make sure that the dog isn't more than you can handle, while a breeder can't exactly predict what the puppy will turn out like.
Rottweilers are great dogs and wonderfull companions but at the same time they are not for everyone. They need an owner who can be loving and firm at the same time.
Best of luck in whatever choice you make.
I don't believe that sex makes much of a difference, either can be handfull.
Peter