I voted all 3, since Nick USED to be good back before 2007. I know that I may sound like I am jumping on the bandwagon a bit, but MOST content on Nick was great pre-2007. After shows like Mr. Meaty and Naked Brother's Band aired, I could sense that there was a decline in Nick's content (which was right where SB started to lose his luster) and the shows were not as enjoyable. 2009-2011 was another decline for Nick, since SpongeBob was at its worst and there were some terrible shows that aired on the network including Fanboy and Chum Chum, but I still had hope since there were a few good sitcoms like iCarly that were still on air.
When iCarly and Victorious ended, the sitcoms started to get revolting. I mean, I don't find myself enjoying and of these sitcoms and it all feels the same. There are some days where I wished that Nick would just give Dan Schneider a break already. And even in 2016-now with shows like The Loud House, I still feel that the network is just awful. Not in their content, since SpongeBob has gotten better, I'm talking about the way that they treat shows that are not SpongeBob or Loud House. I love SpongeBob, but there is no need to air it 6 hours a day. And of course, we have the worst use of memes that I have ever witnessed: their advertising. I have no words for Nick using le outdated maymays to try and stay hip. I'll just leave it at that.
So yeah, I am ambivalent about Nickelodeon as a whole. The 70s and 80s Nickelodeon were pretty forgettable, 90s Nick, while a bit overrated, is still great since the NickToons started to give the network life, 2000s Nick is where they stepped up their game and made it the best years ever, while 2010s Nick is lackluster.