5 AC, +1 CON
There are 12 common armors with AC 4.
Uncommon armors with restricted classes Cleric/Fighter/Paladin:
7 AC, 7 AC +3 ret, 6/9 AC, 6 AC, 7 AC w/ partial DR, 7 AC, 7 AC with partial DR, 7 AC & silence immune, 7/8 AC, 7 AC, 7 AC, 6 AC, 7 AC, 5 AC + STR, 7 AC w/ partial DR, 6 AC, 6 AC +hp, 6 AC, 7 AC (set bonus)
Average Uncommon armor: 6.6 AC with just over 50% chance of a benefit like +1hp, higher circumstantial AC or DR, retribution damage, etc. So fair UC token would be 7 AC or 6 AC with a benefit. CON is a pretty big benefit but maybe not as much as STR.
Rare armors with restricted classes CFP:
7 AC w/ damage immunity, 5 AC + STR, 7/9 AC, 8 AC (set bonus), 7 AC +2 fort, 7 AC +2 ref, 8 AC, 9 ac -1 ref, 7 AC +2 hp, 8 AC, 7 AC +4 Ret, 8 AC -1 ref, 7 AC +1 dmg, 7 AC w/ damage immunity, 7 AC +1 saves, 8 AC, 7 AC +3 ret, 7 AC + heal 4 on teammate death, 7 AC +2hp, 7 AC
Average Rare armor: 7.25 AC with 70% chance of a benefit like +2 or 3 saves, 3 or 4 retribution, 2 conditional AC, conditional immunity, 2 hp, and 10% chance of -1 ref saves. So 8 AC, 9 ac with a negative, or 7 AC with a benefit.
I came here to sing and collect tokens, and I'm alllll out of money.