Here's my top 5 for each what I think is TV's most over and underrated shows. I would love to hear everyone's feedback.

Most underrated:
1. In the Heat of the Night
2. Mary Hartman, Mary Hartman
3. Mama's Family
4. Kate & Allie
5. The Neighbors

Most overrated:
1. The Cosby Show
2. The Office
3. Modern Family
4. Arrested Development
5. Happy Days

Don't get me wrong, I love "The Cosby Show" and "Happy Days", I just think they're hyped up to be more than what they are.

Most overrated
1. Will & Grace
2. Sex and the City
3. Friends
4. All in the Family
5. The Golden Girls

Most underrated
1. Dag
2. Benson
3. Hope & Faith
4. Mad About You
5. Family Affair

Most overrated:
1. The Cosby Show
2. Home Improvement
3. Full House
4. Happy Days
5. Duck Dynasty

I like "The Cosby Show" and "Happy Days", I just think they're overrated.

Underrated:
1. Remington Steele
2. WKRP in Cincinnati
3. Murphy Brown
4. Mama's Family
5. Doogie Howser, M.D.

I'd say the most overrated are:

Facts of Life
Three's Company
Brady Bunch
One Day at a Time
Diff'rent Strokes

Most underrated:

Beverly Hillbillies
Bob Newhart Show
Odd Couple
Barney Miller
Green Acres

"3s Company" and "Brady Bunch" I agree on overrated, but the other 3 aren't.

current Most underrated:
#1 Arrow
#2the flash
#3 gotham
#4 agents of shield
#5 person of interest

current Most overrated:
#1 the walking dead
#2 vampire diaries
#3 super natural
#4nashvile
#5 big brother




Most underrated:
1. lost in space
2. Mama's Family
3. boy meets world
4. step by step
5. hangin with mr cooper

Most overrated:
1. The Cosby Show
2. the andy griffith show
#3good times
4. cheers
5. all in the family

Most Overrated:

1. Seinfeld
2. Arrested Development
3. Modern Family
4. Curb Your Enthusiasm
5. The Jeffersons

Most underrated:

1. The Beverly Hillbillies
2. The Phil Silvers Show
3. Car 54, Where Are You?
4. Make Room For Daddy
5. The George Burns and Gracie Allen Show

Overrated:

Modern Family
The Honeymooners
I Dream Of Jeannie
The Facts Of Life

Underrated:
Who's The Boss
Top Cat
Newhart
Soap
Petticoat Junction

Overrated:
1. Boy Meets World
2. Happy Days
3. Home Improvement
4. The Big Bang Theory
5. The Fresh Prince of Bel-Air

Underrated:
1. Mad About You
2. Cybill
3. Partners (CBS)
4. The Fighting Fitzgeralds
5. Welcome to New York

Most underrated:
1.Mary Hartman, Mary Hartman
2.The Bill Cosby Show from 1969,ran 2 seasons

Most overrated:
1.The Cosby Show
2.The Golden Girls
3.Home Improvement
4.Full House
5.The Big Bang Theory

Overrated I'd say pretty much any 'dark', 'cynic' or 'skeptic' show airing in these last years: Breaking Bad, True Detective, Homeland, Game of Thrones and so on. Praised beyond merits, . Also, two sitcoms that I never understood how they became so popular: Big Bang Theory and How I Met Your Mother.

Can't think of many underrated show, but one of them is certainly Friday Night Lights. It did win some emmys, but it should've been more popular. It was really a great show.
Also, Seventh Heaven has always been ridiculed and laughed at only because it was a family show. Truth is, it was the only show aiming at a certain audience, and for many seasons it was good entertainment for its audience.