Creative Market is well-known for their enormous collection of high-quality mockup templates. If you're looking for a huge volume of mockups to choose from, Creative Market is one of your best resources. "Professionalism" and "realism" is the general atmosphere of their website and mockup selection. Especially if you're looking for mockups that have a modern, sleek, luxury, or minimal appearance, Creative Market is an excellent choice.
Additionally, their search results tend to be extremely accurate in outputting relevant mockups that correspond to your needs and queries. Their filters allow you to refine your search results to find exactly what you're looking for — with advanced filter options that include "File Type", "Price Range", "Software Type", and more. Basically, no matter what type of mockup template you're looking for, and no matter what filetypes or software programs you use for your graphic design workflow, you should be able to find the type of catalog mockup that you need on Creative Market.
Additional Resources: