Both reach-in and walk-in freezers have different strengths and are useful in different ways to your restaurant or catering business.
Walk-ins can have a larger space where it's easier to take a look around and see everything- or almost everything- that is currently stored. Because reach-ins are designed to line up snug against walls, and if you have a lot of stuff to store you may need multiple units, or large units, in order to meet your needs. Also with walk-in freezers, it is easier to make the space fit your storage needs; if you are storing large pieces of meat that may be difficult to wrangle in and out of a reach-in. And of course, it's convenient for deliveries. When you get a lot of frozen goods in, it makes unloading the truck slightly less urgent when you have a walk-in freezer that can keep things below temp while awaiting storage.
Of course, there are some negatives. The first of which is that working in the walk-in freezers is deeply uncomfortable. Freezing temperatures mean that the poor soul putting up the truck and anybody who fetches anything out of the freezer is plunged in and out of an extremely cold environment. Of course, you can, and should, keep gloves and coats on hand so that anybody working in the freezer for more than a minute or two has protection against the cold, but adding discomfort to an already unpopular chore just makes it harder to get it done. Additionally, the door might be heavy, and getting in and out of a walk-in freezer quickly isn't always possible.
Reach-ins, while they are more shallow, are much easier to position where you need your frozen goods that have to be ready to hand. You can place them right by prep areas and in the kitchen. And of course, there are buildings where for architectural reasons it might be impossible to fit a walk-in, and in those cases, you'll need a reach-in.
Many restaurants actually use both, a walk-in for deep and long term storage needs, and a reach-in for things that need to be accessed more easily. It really depends on the needs of your restaurant or catering business, as many such things do. Part of keeping your store culture positive and everybody happy at their job is making sure that the workspace is laid out most efficiently for the work you and your employees are doing, so it's important to weigh all the factors when you're deciding on what kind of freezers you need and where you're going to put them. Businesses can save money on big purchases like these by buying used items like a used stainless three door freezer. Doing reserach about what will fit best in the kitchen will save time and money when you find the right freezer.