well the most popular ones are retired by the mlb but the most popular number would maybe be 8 or 21
The Most Popular MLB team is the Red Sox. I'm not just saying that, the MLB posted a pole one year on their website. The most popular vote was the Red Sox. Number 2 is the Yankees.
Usually 2 to 3 for a home jersey a away jersey and a alternate jersey (if have one)
By far the New York Yankees and Los Angeles Dodgers