Seasons organized and named based off actual episode names:
Home Sweet Pineapple: S1-S3 - These are the seasons that started SpongeBob, and to some, these are the only seasons SpongeBob should've had. Seriously, there's no point talking about them. You could watch them for years on end and you'll never get bored. There's always that one scene that'll make you laugh, and heck, it's always a different one!
Imitation Krabs: S4-5(?) - How many Hillenburgs does it take to panic a Nickelodeon? Apparently one when he stepped down. How many Nickelodeons in 2005 does it take to continue where he stood? Surprisingly, maybe about 1.1 of them. Too bad there was only 1. These episodes came so far, and they're genuinely pretty good. There's some immediate classics. I'm always surprised to find Roller Cowards as a season 5 episode. For the most part, Nick did pretty good picking up where he left off, and imitated him well for a while.
Something Smells: S6-8 - Not because it stinks, but because it smells fishy. Not a fishy that reeks, but certainly salmon. These aren't bad to say, but they're bad. See my delima? This stinks. Actually, wait, it doesn't. Gah! See? Do you see? Okay, look, some great episodes, and then some... episodes. Later down the era, it just seems extremely transitional, and there's even a big design change about S8. I'd put S8 in its own era, but I personally enjoy most SpongeBob episodes, and I have about the same feelings for S8 as I do S6 or S7. This IS my list, after all.
Born Again Krabs: S9-11 - Something has changed. Well, apart from the wider view, everything looks different! It's all exaggerated! It feels like a gross out episode but without the gross, and I don't particularly have a fondness for it. It's unfortunate too, because the writing is actually really good most of the time! Some people came back to help with the show, and it took a turn for some greatness. I just wish, again, they didn't rubberhose the animation neck and bone. Also coming with the 2nd movie, it was for sure the rebirth of SpongeBob and it's popularity. Especially for this site, where it even got like 200 members online in 2016.
Missing Identity: S12-TBA - We last leave on the most modern of eras. Anything to write home about? Nah. The show refuses to give itself an identity for most of the time, as it gets really experimental. I'm sure the team has fun with it though. Rubberhose stuff is tuned up even more, and the writing can get crazy. They continuously try to bring back or reference old Spongebob characters and jokes. The show continues to get zanier and zanier the more it goes on.