The other aspects such as colour, special design and material as obviously natural materials are better than synthetic ones, depending on your personal preference and your budget, the most important aspects that you should look at in a mat before buying it is firmness, grips, and size
It is highly recommended to use your own mat for hygiene reasons and especially during this pandemic crisis if you have no other option to use an existing mat on your yoga venue, make sure you take your spry sanitiser or disinfectant wipes to clean it before use.
Hope this helps you in making your decision, as you need to balance your requirements based on your personal situation such as injuries, age, the type of yoga, floor and your budget