Regarding top ten shows from '80 to the present...
Seinfeld, obviously, is one of them, and I'm sure all of us in this newsgroup agree to that.
Simpsons, definitely another.
Married With Children (early episodes, anyway, although the funniest episode of the series did occur in the mediocre later years, the one where Al goes to Chuck E Cheese and BUd is having an affair with two coeds).
Unhappily Ever After...essentially a controlled experiment by 1/2 of the team which created Married (controlled in the sense that it occupies the same time slot and is on an upstart and is positioned to be an anchor): can you clone a hit show and duplicate its success (they inverted a couple of the formula elements [e.g. the girl is smart and the brother dumb], but it is essentially the same, down to some specific plots), especially on a netlet which is even more of a startup than Fox was during its prenatal infancy? Of course, probably the biggest asset of this particular show is Tiffany, and I've got a question (sorry if this ? offends anyone, but I'm just curious and have not been able to find this info out): does anyone know if Nikki Cox's breasts are real?
Drew Carey Show, Working, Just Shoot Me...probably fair to include them on the list (and this talk of Just Shoot Me taking over Seinfeld's slot: not a bad choice, but the show can get slightly sentimental at times...better off at 9:30...Working might be a better replacement [can I get a 'hell, yeah!' from all the Devo fans out there?]).
Now, let me tell you what my favorite show of the last few years is: Weird Science. One of the best shows ever. The Hughes movie was horrible (don't know if the legend is true or not, but they say he wrote it in two days) but the TV series accentuated all the good parts which were only exploited to miniscule levels in the celluloid treatment of the concept. Great acting, great comedic timing, superb spfx, wonderful cinematography, sharp writing...and the idea of having a female-fantasy genie at your disposal is beyond enticing (as was the actress who portrayed the wish-granter, Vanessa Angel).
Parker Lewis Can't Lose...essentially a brand extension of another Hughes project, the indefatigueably popular Ferris Bueller's Day Off. But hey, why grab the rights when you can just make a show basically close to another idea without comprising any copyright statutes (I believe Mike Nesmith said somethng similar in regards to a song the Monkees were composing which started out as a cover; said something like, 'Why do we need to do a cover? We can use some of the chord progressions, but put our own melodies in. [not an exact quote]). Interesting to note that basically the same creative team behind Weird Science TV show were present on this one (although, comparing both shows from stylistic points of view, one would be disinclined towards any species of surprise). Parker Lewis was a cool, odd show, fashionably topical like Miami Vice was (a serious disadvantage in terms of mainstream syndication), but very fun, as all quirky/surreal high school shows are.
Can't think of a tenth right now, but here are nine good shows from '80 to present, at least. Seinfeld's almost over, gang, we're getting down to the wire. I think there are 8 left, or something like this. How long has he been on- nine years? Too bad he didn't go to ten, for symmetry's sake (I'm talking 'even' symmetry here; some mathematicians might point out that nine may be more of a symmetrical number...anyway...); also, by duking it out one more year, there could have been more of a buildup to the departure. Later, Vader...