You should always use the 10 unless the guy is on your 40-man and you need the spot open. Putting a 40-man roster player on the 60-day IL temporarily clears a spot on your 40, allowing you to add a player to the roster without designating another for assignment.
The IL days are just a minimum, if he is out for 22 days he can be activated after 22 days (and so on). If he is out for 75 days, he’ll be out for 75 whether you put him on the 10-day or 60-day. Thats why it doesn’t matter for guys that aren’t on the 40-man. Just dont put a guy in the 60-day if he is going to be out for less than 60 days (which it sounds like you did with Benintendi, lol).