Clemente was before my time but had a great arm.
Dave Parker was before my time too but I’ve seen good clips of his arm.
I’d give the nod to Roberto.
Clemente had the best arm I saw live at a game. Stargell had a cannon too until his knees gave out and moved to first. Parker would be second to Clemente. He took a little longer to uncork one. But there were many great outfield arms. Ichiro is overlooked because of his hitting but many baseball people say his arm was as strong as Roberto’s