Now, some of your results will be links to companies that sell embroidery digitizing software. If you have no interest in trying to digitize your own embroidery patterns, then you have no need for the links to the software companies. Ignoring those will bring down the number of companies that you can consider when you choose an embroidery digitizing company.
Where you will want to start with your comparison of the embroidery digitizing companies is with the prices and the turnaround. Some companies will offer a fast turnaround (starting at 24 hours). Some will not advertise a turnaround at all for their embroidery digitizing services. You may need to email the company to find out what their turnaround rate is.
The next place you will want to look is at how much the company is charging for their embroidery digitizing service. Prices can vary greatly, and you need to decide on what you feel is a fair price for you to pay. You will probably want to comparison shop to come up with the price you are willing to pay. In some cases, you may get a bulk discount.
The final thing you will want to look at when choosing an embroidery digitizing company is at the quality of their work. Most companies have examples of the items they have digitized on their website. If their examples aren't up to the standards you want for your digitized embroidery pattern, then you should probably look at a different embroidery digitizing company to digitize your embroidery pattern.
Keep in mind, once you decide on the company that you are going to use for your current project, you may still want to comparison shop each time that you have another embroidery pattern digitized.