So, this is mega-subjective. Tons of names can be mentioned.
My list is rather random so don't worry too much. Could also include bgirls too, but I just focused on bboys for this here. Here we go:
1980s: Icey Ice
1990s: Bboy Ivan
2000s: Bboy Physicx
2010s: Bboy Issei
Many other names could replace some; bboy k-mel in the 1990s, bboy Cico was epic as well as bboy Brahim or bboy Blond or bboy The End. Or in the earlier days also bboy Storm, bboy Gombi - too many to name really. I am much weaker past 2020 as I have not been following the scene as closely as I did in the 1990s.