Gintama is really not all of that great.
Naruto isn't quite as bad as the massive hatedom makes it out to be. I've watched/read a fair number of Shonen, and Naruto, at least, has feeling/emotion to it. Sure, it's still overtly cliche in many ways and is also ridiculous. I'm not saying it's a masterpiece, or even anywhere near the best of its genre, but this series isn't worth the unbridled hate it gets.
As far as Shonen goes, the ones I've watched/read that have been the most bland and lacked any real care from me have been Fairy Tail (initially I found it enjoyable, later on... Not so much) and The Seven Deadly Sins. These are just cliche after cliche, and they feel forced. SDS is even worse for me for other reasons. My Hero Academia also seemed rather bland by the time the first season ended, but it's unfair to judge it completely from that, I suppose. Katekyo Hitman REBORN! was also fairly overrated. Not quite as bad as Fairy Tail or SDS, but I really hated how they treated female characters in that series. Plus, there were some very annoying characters.
I agree with Catcake that Hunter X Hunter is an amazing series. I don't know unpopular that opinion really is, though. It just seems like not a lot of people have bothered with HXH. You can't blame them, with all of the hiatuses, I suppose. And then there's the fact that the image of the series makes it look like it will the most blanded, cutesiest Shonen ever. Boy was I wrong thinking that before watching it. LOL. Not all of it was super amazing, but in many places it subverted Shonen cliches, and the way that last major arc ended in the anime just kind of blew me away.