mine are
#1 Quantum Leap
#2 person of interest this one really shocked me!! it was just getting better & better each seaon!!
#3the mentalist
#4 smallville
#5early edition
#6 seven days
#7 flash forward
#8 kyle xy
#9 forever
#10 moon light

sitcoms
#1 the wonder years
#2 boy meets world
#3 night court
#4 family ties
#5 step by step
#6 happy days
#7 hanging with mr cooper
#8 the jeffersons
#9mama's family
#10 perfect strangers

Quantum Leap- Was initially cancelled in the middle of the 3rd season and it was brought back due to a mail-in campaign
Happy Days & The Jefferson- were on the air for 10+ seasons and were past their creative prime
Perfect Strangers- was shifted around a few times in the later seasons which is usually a sign that it will be cancelled.
Wonder Years- Agree with you on this one. They should kept it on for at least one more season where Kevin could graduate high school and go off to college. The ratings were still solid in the final season.

Older shows that you did not mention:
"What's Happening!"- was getting solid ratings in season 3. Fred Berry and the other actors apparently demanded a huge raise. The network execs decided to not give in and cancel the series. Reruns did well in syndication which promptly a follow up series "What Happening Now!"
"Lou Grant"- Was doing well in the rating but reportedly cancelled due to Ed Asner's political views
"Gidget"- Initially got poor ratings but ratings really improved in the summer. Instead of un-cancelling the series, ABC decided to give Sally Field another sitcom- "The Flying Nun"

Just The Ten Of Us. This show was good and was doing decent in the ratings. It won its timeslot I believe. However, because ABC wanted to just use Miller-Boyett productions in its highly rated Friday slots (was it TGIF then?) they decided to move it but couldn't find a spot so they cancelled it. I remember reading they considered bringing it back but it was too late.