I have been grading NBA prospects since high school.
Nothing too complex, I use the eye test, look at some data and look for NBA ready players once they enter the league. The process has changed a bit over the years so this has a bit of a curve to it.
I went back and looked at who my highest graded players were since 2020 and did an overall draft for fun based on the rankings:
Top 10:
1. Victor Wembanyama (A+)
2. Cooper Flagg (A+)
3. Paolo Banchero (A+)
4. Chet Holmgren (A+)
5. AJ Dybansta (A+)
6. James Wiseman (A)
7. Cade Cunningham (A-)
8. Caleb Wilson (A-)
9. Ace Bailey (A-)
10. Jalen Green (A-)
Full list below. I may have got fired if I selected 6/9/10 haha.