What exactly do you mean by "HD"?
We live in a world where the word HD has come to sound like something ubiquitous. A lot of clients think to themselves, "We'll shoot it in HD and it will look great." What those who are production-seasoned will tell you is that the spectrum of what is called HD is so wide and so varied, two companies could both call their video production offerings high definition and be delivering two completely different end products.
How HD is your HD?
Ask your potential production company what exactly they mean by an "HD" camera? Do they mean 720p? Do they mean 5k (5000 pixels across)? Somewhere in between? Do they mean a 5D or an Alexa or an iPhone? Technically they all shoot in HD. Which leads to the second point:
What kind of footage does it record?
Many DSLR cameras record a highly compressed, low-information format that you can't do as much with in the computer later on. There are other variables that lead to the sort of pristine, rich image that makes your clients associate your commercial or video production with a serious, successful business. There's a reason they don't film hollywood blockbusters on 7D's.
Remember how exciting it was when you could record pictures and videos on your old flip phone? But look at them now...they don't look so great do they? Sometimes marketing materials only need a short half-life, but other times you want to create materials you can remix and recycle and get great mileage out of over time. Choose a production company that can get you the most out of your investment by selecting the proper format for your production.