Not the "finest". Take away his 2:06 and you get a 2:08/2:09 guy.
Strictly speaking American born marathoner, Bill Rodgers is by far the best. His 2:09:27 PR compares to Hall's 2:08:40 non London PR. Plus waaaaaay more wins, world rank #1's, waaaay more races. All this in the "amateur" era without the cushy shoe contracts, and with "only" 1970's sports medicine, waaay less PED available.
Bill Rodger's record at his peak:
# 1975 Boston (2:09:55) 1st American Record (AR)
# 1975 Enschede Marathon, Holland (DNF)
# 1975 Fukuoka Marathon (2:11:26) 3rd
# 1976 Olympic Trials (2:11:58) 2nd
# 1976 Montreal Olympics (2:25:14) 40th
# 1976 NYC (2:10:10) 1st CR
# 1976 Sedo Island, Japan (2:08:23) 1st CR (200 meters short)
# 1976 Maryland (2:14:28) 1st CR
# 1977 Kyoto, Japan (2:14:25) 1st
# 1977 Boston (DNF)
# 1977 Amsterdam, Holland (2:12:46) 1st CR
# 1977 Waynesboro (2:25:12) 1st
# 1977 NYC (2:11:28) 1st
# 1977 Fukuoka (2:10:55) 1st
# 1978 Boston (2:10:13) 1st
# 1978 NYC (2:12:12) 1st
# 1978 Fukuoka (2:12:53) 6th
# 1979 Boston (2:09:27) 1st AR
# 1979 Montreal (2:22:12) 15th
# 1979 NYC (2:11:42) 1st
# 1980 Boston (2:12:11) 1st
# 1980 Toronto (2:14:47) 1st
# 1980 NYC (2:13:20) 5th
# 1981 Houston-Tennaco (2:12:10) 1st CR
# 1981 Boston (2:10:34) 3rd