Takes a bit longer to use a pin retainer if you change sockets often. You'd have to align the hole on the impact socket with the pin to achieve the best results. Once they're on there's no way you can lose the socket (great for heights, factories and assembly style jobs). Removing socket from the anvil will require a small pick or screwdriver to unlock the pin.
Hog ring retainer is good if you change sockets often throughout a job. The rings (both metal and rubber) are wear and tear items and loses their effectiveness over time. Expect to replace them when they've worn out or lost.
Either design will require the use of impact sockets (those with holes on the side), as chrome sockets will ruin both anvil designs. Have fun removing a chrome socket from a pin anvil, and lose the hog rings on your ring anvil. The detent inside chrome sockets are designed to be used with a ball type retainer (the ball will roll off the detent), but not pin retainer (which requires a hole through socket to unlock the pin, chrome sockets have no holes on the side) or ring retainer (the hog ring catches with the detent and gets yanked out with the socket).