Not sure if this has been done on here before, but I had this idea, so here goes...
1. Bill Oakley & Josh Weinstein - Seasons 7 & 8 are among the best seasons of the series in my opinion. At this point, the show was running so long, there was a lot you could do with it and they used the potential to its definite fullest. Season 7 has some of the most well-written family centered stories, such as Home Sweet Homediddly-dum-doodily, Summer of 4'2, and Marge Be Not Proud. People are probably going to down-talk season 8 for its experimental edge, but the experiments are what made the season great in my opinion. As I mentioned before, the show was so well formed at this point, there was a lot you could do with the show's universe and the experiments gave the show depth. (By the way, I am aware of the hate for Principal and the Pauper. I can't say it particularly bothers me because it's one of the first episodes I remember watching, so Skinner was always Armin Tamzarian in my mind. I will admit it's my least favorite O&W episode, however, but that's more because of the lack of humor.)
2. David Mirkin - Season 6 is my personal favorite season, but David Mirkin comes in at number two because season 5 is among my least favorite classic era seasons. David Mirkin's episodes are probably the funniest of the series, and even when I watch stuff from him I've already seen a thousand times, I am still in awe of his great comic timing. Season 6 is my #1 season because it does the best at blending comedy and empathy. Season 5 was pretty good, but it got carried away with the silliness at times.
3. Al Jean & Mike Reiss - These guys set the bar for the guys above. Season 3 was a touching and well-written season and it helped the show's segue into being recognized as a comedy. I feel that season 4 is overrated, however. Yes, I will admit it's a great season, but it just feels too simplistic compared to some of the other seasons before and after it. I can't view it any other way than "classic."
4. Matt Groening, James L. Brooks & Sam Simon - The guys who started it all. These guys took a series of simple cartoon sketches and made it into a cultural phenomenon, which is definitely more than worthy of admiration. The realistic feel that the first two seasons had gave the early episodes a certain charm that resonates with me. They'd be ranked higher, however, if they didn't rely so much on sitcom cliches.
5. Mike Scully - I'm sure just reading that name means death to you boarders. I can relate. Mr. Scully took over the show when it was at its best and in a matter of time, quickly turned it into a cynical gag-fest with unrelatable characters and a plethora of shamless celebrity usage. It happened rather quickly, too - his season 9 episodes are decent with only a handful of them showing glaring Scully problems. The first few episodes of season 10 feel like the better season 9 episodes, but along the way, you definitely see something amiss. While seasons 10-12 probably excel compared to today's stuff, they are still crap compared to the classics and I still feel that Mike Scully screwed up a great show.
6. Al Jean - I was very hesitant to put him as the worst, but his last few seasons have earned him this. His first four seasons, while not classics, put the show back on track to being relatively enjoyable, but he overstayed his welcome when the 17th season rolled around and it brought the show to the point where it was worse than any offenses Scully commited. It got slighly better when the seasons entered their 20s, but they are still worse than Scully's crap.