I'm going to post the nutritional info for both brands here, to make it easier for our nutrition experts to evaluate. I assume you're talking about dry food; I couldn't find a wet version of the Purina Beyond chicken and egg.
Purina Beyond White Meat Chicken & Egg Recipe Grain-Free Dry Cat Food, 5-lb bag Nutritional Info Ingredients
Guaranteed Analysis
Crude Protein 35.0% min
Crude Fat 14.0% min
Crude Fiber 4.0% max
Moisture 12.0% max
Linoleic Acid 1.3.0% min
Calcium 1.0% min
Phosphorus 0.9% min
Zinc 150 ppm min
Selenium 0.35 ppm min
Vitamin A 12,000 IU/kg min
Vitamin E 150 IU/kg min
Wellness CORE Grain-Free Indoor Formula Dry Cat Food, 11-lb bag Nutritional Info Ingredients
Guaranteed Analysis
Crude Protein 38.0% min
Crude Fat 12.0% min
Crude Fiber 5.0% min
Moisture 10.0% max
Calcium 2.20% max
Phosphorus 1.6% max
Vitamin A 25000 IU/kg min
Vitamin E 200 IU/kg min
Taurine 0.2% min
Omega 6 Fatty Acids 3.0% min
Omega 3 Fatty Acids 0.5% min
Total Lactic Acid Microorganisms 90,000,000 CFU/lb min
I think they both look like pretty good foods, because they're grain-free and have meat as the first ingredient. I think I'd give the Purina Beyond an edge, though, because it's potato-free, (cats are obligate carnivores, so starchy vegetables like potatoes are like empty calories for them), and also has a shorter ingredients list.
I'd go with wellness. It has a lot more meat in it that the purina. I also used to feed it in my rotation and my cats always did really well on it. I also try to avoid touching anything purina unless I have a 6ft pole.