I think 680 might win the prize.
AM stations
WHBQ has only had 8--Mutual network, top 40, oldies/AC, news/talk, oldies, oldies/heavy metal, country, sports.
WREC about 4--CBS network, MOR, Music of Your Life, News/Talk.
WMC about 6--NBC network, MOR, Country, News/Talk, Sports, Classic Country
WDIA & WLOK always some form of urban except for the first few months of DIA.
KWAM probably 4--Country, Gospel, Black Gospel, Talk.
WBBP also probably 4--Easy Listening, Country, Christian, Black Gospel
1430 could be a contender--Easy Listening to about 1973, Talk to the mid 1980s. After Sam Phillips sold the station, they were Standards, CNN news, and a bunch of other things prior to Radio Disney. Weren't they even modern rock?
FM
92.9--3 classic hits, active rock, modern rock
94.1 or 94.3-- I think about 8, MOR, top 40, country, easy listening, oldies, country, modern ac, rhythmic ac.
95.7--3 modern rock, oldies, black gospel
97.1-- 2 classical, urban
98.1--5 since moving to Memphis, AOR, top 40, oldies, classic hits, classic rock
98.9-- 3 since moving to Memphis, smooth jazz, urban, variety hits
99.7--4 or 5, AM simulcast, top 40, AOR, top 40, hot AC
101.1--about 5, easy listening, country, black gospel, urban, urban AC
102.7-- maybe 6, easy listening, country, AOR, top 40, AOR, classic rock
103.5-- 1 since moving to Memphis, urban oldies
104.5--3 religion, easy listening, adult contemporary
105.9--3 Drake Chenault hitparade, easy listening, country
107.1--? I think they were black gospel (KFTH), urban AC, modern rock, blues, urban maybe something else.
107.5--? top 40, dance, AAA, top 40. Maybe others