I have 6 American 1100 padlocks and 6 master lockout locks (well now 4 because 2 i rotated all the way and the pins fell out

I am getting to the point that I rotate thru the 12 locks too quickly and its not as fun.
So now I am trying to decide should I just get more of the same locks as they seem to be some of the most challenging pin-tumblers or can someone recommend others that are more challenging?