I think achievement NFTs being soulbound is nice. I played a mobile game called Nikke and they have these world records on the top 10 players who cleared this stage and it's going to be there for the rest of the server to see. But the servers are separated into mini-servers of shards in the record keeping, SEA server having multiple sub categories and players are lumped together based on the time the account was created. This lets beginners play competitive among their peers that started during the same time.
Since Nikke was released more than a year ago, it's impossible for me to get any top 10 on clearing anything but because of this system, I'm lumped with other players that started around the same time and I can make the records as the first person to clear the stage among this batch. It doesn't affect the other batches because they have their own top 10 but it gives new players some motivation to set their own world records. Well, this is why I'm hooked into the game even if it doesn't pay me back anything, I'm the currently rank 1 on some achievements and that's just personal bragging rights.
Yeah personal records are probably a great idea too!
Not sure if I asked this before, but would there be ways to undo the soulbound, like burning some substantial amount of ZING just to pass the perks of that NFT to another player?