mine would be
#1 the wonder years
#2 Quantum Leap
#3 Early edition
#4 numbers
#5 the dead zone
#6 seven days
#7Kyle xy
#8 flash forward
#9 journeyman
#10 jon doe

Lincoln Heights

Uncle Buck

Gidget

I Dream of Jeannie

Julia

Everybody Hates Chris

Mistresses

1. Mama's Family

2. Reba

3. The Walton's

4. The Wonder Years

5. The Love Boat

6. Lou Grant

7. Chips

8. Emergency

9. Evening Shade

10. Carol Burnett

I could go on and on...

I can answer why some of the show's above got cancelled.

Wonder Years. Basically the kids grew up. Might have been good for one more year, but the ratings were probably falling, Danica McKellar probably wanted to go to college (she is a literal genius) and again, Fred Savage wasn't a cute little boy anymore.

Lou Grant. Ed Asner got in trouble with CBS because Asner said something in support of the Sandinistas in Nicaragua, and basically this is why Asner got canned, and again, probably because of falling ratings. Asner is very, very liberal, almost Communist really. I love the guy and he is a beloved guy and I think he has been smart enough to usually keep the Hammer and Sickle in the closet when there are lots of cameras.

Carol Burnett Show was simply because the ratings fell and variety shows were on the way out. That show was on from 1967 to 1978.

1. That '70s Show

2. Roseanne

3. The Nanny

4. Reba

5. Gilligan's Island

6. Three's Company

7. The Fresh Prince of Bel-Air

8. Full House

9. The Golden Girls

10. F.R.I.E.N.D.S.