I just don't really prefer rap and hip hop on its own. I'm sorry. I love rock with a mixture of hip hop or rap. IMO, I don't think it's fair to say that the best albums came from the Hip Hop genre coz it's a matter of preference.
On the rock tho, It seems like rock is dying now and the rock bands are trying to change their sound to fit the current preferred genre. I'll beg to differ tho on you saying that the (Alternative) Rock bands we have now suck. With the exception of the new Maroon 5 and Coldplay, almost every current rock bands we have now are still as good as they were.( but they're pretty few now.) It's just that they don't do, you know, the classic lineup which just uses electric guitar, drums, bass and vocals. Bands nowadays would always use too much synthesizer (the electronic sound) on their music to make it more livelier and appealing.
Maroon 5 is a great example of this. they would only use electric guitar and piano/keyboard on their music before. Now, they're a full blown electronic pop rock band. But they're kinda sucky now anyways. Their music has now this "dance club song" vibe compared to their old "cafe-type song". I mean just listen to "She will be loved" then listen to "Moves like jagger", you'll get what I mean. One thing that I still love about their music tho is that they still retained that jazzy sound eventho they jumped genres.
I dunno if you heard the new OneRepublic song but it seems like they're going down the same road where Maroon 5 headed. I hope they really don't. They're one of the remaining few good bands out there.
Also, the current mainstream music isn't that completely bad that I would write it off. I mean you have musicians like Adele, Sam Smith, John Legend, Charlie Puth, Bruno Mars, Ed Sheeran etc etc who reigns the charts and all of them are phenomenal singer-songwriters.