Please don't take my post the wrong way at all - it is fantastic that you are starting to do some research before you get a dog so many people don't do this.
However some of your comments and replies do show that you have nominal knowledge of dogs and what they need. This is not a dig at all but you do need to do a lot of hands on research to ensure that getting a dog is the right thing for you.
Your fear of some dogs as you say may be irrational but if you have a dog you will meet loads of other kinds of dogs - you will need to be dog savvy if you are to have a happy dog yourself.
Dogs are a major commitment obviously. I personally have changed my career to ensure that I can have dogs otherwise you will need to be prepared to get up early to exercise the dogs before you go to work, pay for sitters or walkers and be prepared the minute you get back home to go out with the dogs again. This is daily not just when you feel like it or have time, it is when you son is ill and cann't be left, it is when it is dark and peeing down with rain, it is when you are exhausted after a grueling day at work. Days out will have to be planned can the dog come, who will look after the dog etc.
Dogs can bring their own individual issues. You may be lucky and get a dog that is happy to be left alone and is chilled and laid back, you may get a dog that barks, has separation anxiety, jumps up, chews and has poor recall. Some dogs need more time than others and this is hard to determine before you get the dogs - rescue dogs are assessed but with your work hours I am not sure all rescues will home to you. Also rescue dogs can behave very differently in rescue to being in a home situation. You have to be prepared to train and sort out any issues and this may mean changes to your lifestyle and your expectations of dog ownership - if you are not prepared for this maybe a dog is not for you.
Can you contact local training classes and go and watch - most people will talk happily about their dogs and you can see the training required, you could also walk with the owners to see exercise requirement of individual dogs. (I hope there is a staffy there as they are the kindest, lovable fun dogs and you may change you mind!)
For many people dogs are a way of life not something that is added to an existing life and those generally are the happy, stimulated healthy dogs.
Can I ask why you want a dog?
What is it that you want from a dog?
What are your daily expectations from the dog?
What do you expect the dog to bring to your life?
How much time daily are you prepared to give to the dog?
What are your plans for the dog when you have a long day working?
What if your son does not like the dog or is annoyed by its jumping up?
Do you want you son to be able to walk the dog on a lead or just you and you OH?
I am assuming money is not a problem if you are both working but a yearly cost of a dog is part way to a good holiday every year are you happy to spend that on a muddy time consuming hairy dog 