[AF#15-ASM#38] + [ASM#39-120] + [Spectacular Spider-Man Magazine] = [AF#15-ASM#120]
NB: I only took into account their appearances in Spider-Man comics but not elsewhere. For example, Sandman's appearance in Strange Tales #115 is not counted.

(1) Green Goblin / Norman Osborn
9+11+1=21

(2) Doctor Octopus
8+11=19

(3) Lizard / Curt Connors
3+11=14

(4) Kingpin (& Schemer)
0+12=12

(5) Kraven the Hunter (& Gog)
4+7=11

(6) Vulture(s)
4+(1+1+2)=8

(7) Mysterio
3+3=6

(8) Spencer Smythe & Spider-Slayers
2+4=6

(9) Sandman
4+0=4

(10) Enforcers (Montana, Ox, Fancy Dan)
3+0=3

(11) Scorpion / Mac Gargan
3+0=3

(12) Chameleon
2+1=3

(13) Electro
2+1=3

(14) Rhino
0+3=3

(15) Silvermane (& Man Mountain Marko, Big C)
0+3=3

(16) Hammerhead
0+3=3

(17) Molten Man
2+0=2

(18) Beetle
1+1=2

(19) Shocker
0+2=2

(20) Morbius
0+2=2