I have used a list of shows by the year they debuted that can be found at Episode Guides to pick what are, in my opinion, the 25 best years for TV Show debuts. Originally, I was going to penalize years for bad shows, but as I reviewed the lists, I realized that that would penalize recent years too much, so this Top 25 is based just on what I consider good. "Good" can mean different things as well. Sometimes, it is quality. Sometimes, it's merely entertainment value.
25) 1961—The Dick Van Dyke Show
24) 1995—Cybill; The Drew Carey Show; JAG; NewsRadio; Pinky and the Brain; Sliders; Star Trek: Voyager; Xena: Warrior Princess
23) 1981—Cagney & Lacey; Hill Street Blues
22) 2003—Arrested Development; The Joe Schmo Show; MythBusters; Nip/Tuck; Reno 911!; Teen Titans; Two and a Half Men
21) 1970—The Mary Tyler Moore Show; McCloud; The Odd Couple
20) 1999—Family Guy; Freaks and Geeks; Futurama; Law & Order: Special Victims Unit; Who Wants To Be a Millionaire?
19) 1987—Beauty and the Beast; A Different World; Full House; Married ... with Children; Star Trek: The Next Generation; thirtysomething; 21 Jump Street
18) 2001—The Amazing Race; Enterprise; Justice League; Law & Order: Criminal Intent; Scrubs; The Tick; 24
17) 1994—Chicago Hope; The Critic; Duckman; These Friends of Mine/Ellen; ER; Friends; My So-Called Life; Space Ghost Coast to Coast
16) 1965—Get Smart; Hogan's Heroes; I Dream of Jeannie; Lost in Space; The Wild Wild West
15) 1960—The Andy Griffith Show; The Flintstones
14) 1996—Arli$$; Early Edition; Everybody Loves Raymond; The Pretender; 7th Heaven; Spin City; 3rd Rock From the Sun
13) 1975—Baretta; Barney Miller; The Jeffersons; Saturday Night Live; Starsky and Hutch; Welcome Back, Kotter; Wonder Woman
12) 1966—Batman; Family Affair; The Lone Ranger; Mission: Impossible; The Monkees; Star Trek
11) 1955—Alfred Hitchcock Presents; Gunsmoke; The Phil Silvers Show
10) 1990—Beverly Hills, 90210; Evening Shade; The Fresh Prince of Bel-Air; Get a Life; Law & Order; Northern Exposure; Parker Lewis Can't Lose; Twin Peaks; Wings
9) 1997—Buffy, the Vampire Slayer; King of the Hill; The Practice; South Park
8) 1957—Have Gun - Will Travel; Leave It to Beaver; Maverick; Perry Mason; Wagon Train
7) 1972—Bob Newhart Show; Kung Fu; M*A*S*H; Maude; Sanford and Son
6) 1989—Alien Nation; Coach; Doogie Howser, M.D.; Life Goes On; Quantum Leap; Saved by the Bell; Seinfeld; The Simpsons
5) 1993—Babylon 5; Beavis and Butt-head; Boy Meets World; Frasier; Lois & Clark; NYPD Blue; Star Trek: Deep Space Nine; Walker, Texas Ranger; The X-Files
4) 1959—Bonanza; Dennis the Menace; Rawhide; The Twilight Zone; The Untouchables
3) 1974—Happy Days; Kolchak: The Night Stalker; Land of the Lost; Little House on the Prairie; Police Woman; The Rockford Files
2) 1978—Battlestar Galactica; Dallas; Diff'rent Strokes; Mork and Mindy; Taxi; Vegas; The White Shadow; WKRP in Cincinnati
1) 1982—Cheers; Family Ties; Newhart; Police Squad!; Remington Steele; Square Pegs; St. Elsewhere
1951—I Love Lucy
1976—Alice; Charlie's Angels; Family; Laverne & Shirley; Quincy, M.E.
1984—The Cosby Show; Night Court
1985—Amazing Stories; Growing Pains; Moonlighting
1988—China Beach; In the Heat of the Night; Murphy Brown; Roseanne; The Wonder Years
1998—Sports Night; That '70s Show; Two Guys, a Girl, & a Pizza Place; Will & Grace
2000—CSI: Crime Scene Investigation; Ed; Malcolm in the Middle
2002—Andy Richter Controls the Universe; The Dead Zone; Monk
BTW, I know that the Episode Guides site omits some shows. If you feel there is a glaring omission that might affect the rankings, post a comment and maybe I'll amend.
UPDATE: I removed "The Avengers" from 1961 for two reasons: It debuted in the US in 1966 and it was a British Import. I didn't include any other British shows.
UPDATE 2: Added "Who Wants to Be a Millionaire?" to 1999 and moved that year up to 19th.
UPDATE 3: I had someone point out that I had messed up by overlooking 1957. I demoted 1995 to #11 and moved 2000 to Honorable Mention