I wouldn't class any as holy grail
I think its just a case of whats hard to find at the time
When I started keeping tigers 10 years ago ST were easy to find and ngt were the ones you would have classed as the holy grail
At this point ST are the hardest to find so are considered the holy grail so other tigers were imported in greater numbers to fill the gap ST had left in the Market meaning we saw more ngt come up for sale
If what people are saying is true then ngt surplus is running low so they will also become the holy grail again
Different people have different ideas on the holy grail for me I have only ever found 1 thin bar with full neck band but it got killed and I have been looking again for over 4 years
You can get ST if you are willing to pay but no point in getting a ST just because it's a ST if it looks crap
I would much rather a nice looking ngt NTT or it than a crap looking ST