In no particular order:
Pink Floyd
Red Hot Chili Peppers
Grasshopper Pie
311
O.A.R.
OK you guys probably don't care, but I'm gonna talk about each band just because I can and like talking about music.
Pink Floyd will always be my all-time best, favorite, whatever you want to call it, band because I have never heard of music that has spoke to me as much as theirs does. There will never be another band that captures their sound; they are one of a kind. They have about 5 albums that I would say are literal masterpieces, which is way more than pretty much any band can say. Meddle, Obscured by Clouds, Dark Side of the Moon, Wish You Were Here, and Animals. All of those are an experience in themselves, and my personal favorite, Meddle, contains the absolute pinnacle of a Pink Floyd experience, Echoes.
Red Hot Chili Peppers are probably my favorite band that is still around. I've seen them live, and I can testify that they put on a hell of a show. All of their music is so diverse, that I just find myself liking all of the different kinds of music they have out there. They managed to produce an absolutely flawless album, BSSM, and have managed to put out a ton of other worthy listens with some true gems inside such as Mother's Milk, Californication, By The Way, and Stadium Arcadium. They have so much music out there and I pretty much like it all save the really early days(mid 1980s) which I haven't taken enough time to get into. I honestly strive to produce music as beautiful as Frusciante does as a guitarist.
Most people here probably have never heard of Grasshopper Pie. I first heard of GP a year ago, where they put on an absolutely badass show at Tabfest, a music festival put on around here every year. I can't even explain what they sound like, so I'll just c/p what their 
website describes them as:
"The band’s music revolves around tightly arranged, well-written songs, with room for live improvisation. Grasshopper Pie draws inspiration from classic rock and American roots music including blues, bluegrass, country and funk. The band’s sound is its own."
I have yet to hear a band that sounds anything like them, and still manages to jam and improvise as well as they do live. To shamelessly whore out this band a little more, I recommend downloading the 
Tabfest 2003 Grasshopper Pie performance and hearing some of it yourself(they are much, much better live than in their studio efforts). I recommend checking out Colorado, Grasshopper Blues, Scooby Doo, and Harley for starters, but after you realize how catchy this band is you will probably listen to it all. I sometimes want to kill people when I think about how I will never to get to hear this band again, but it works out, I just stuff those nasty nasty thoughts inside.
I didn't really think 311 was that great of a band until I started smoking weed, and then I pretty much realized that this is the perfect stoner music. A lot of pretentious music (BAN ME PLEASE)s will try and tell you that 311 sucks as well as the culture that goes along with it, but I like to think that I choose my music on a basis of how good it sounds, and I can't understand how you can't find this band catchy. P-Nut is the fucking man on bass and delivers consistently funky bass lines, and the vocals are always superb. I just saw these guys play on Friday in Cleveland, and god damn was that a great time. 311 is another one of those bands that has so much music out there. I wouldn't even say they have a really "superb" album, but when you release so many of them there is bound to be some great stuff out there. One song I just discovered from these guys is "Beyond the Gray Sky", listen to that and tell me that doesn't almost sound Pink Floyd-like.
I've loved O.A.R. since I first heard them. A lot of people associate this band with drunken college (BAN ME PLEASE)s, and while that may be true to some point, I still love this band. I can't even think of better drinking/party music then O.A.R.. Some people will tell you how much they fucking hate their lyrics, but once you get past the fact that not every band has to write inspiring thought-provoking lyrics to be good, I think you can get into this band. It's all about having a good time; I love it. Hopefully at Columbus next year they will put on a free show for us OSU students. :)