Unless you are buying directly from a fishing boat, frozen shrimp is often fresher because it is flash-frozen at sea to lock in quality.
Retailers like Aldi and Walmart are cited for having competitive prices on frozen jumbo varieties, such as 21-25 count farm-raised shrimp. where to buy jumbo shrimp
Look for the numbers on the bag. A "16/20" count means there are 16 to 20 shrimp per pound; smaller numbers indicate larger shrimp. Unless you are buying directly from a fishing