Paranoid Android is definitely one of my favourite Radiohead songs, but I think as far as their albums go, as a cohesive whole, The Bends is superior. If you haven't listened to it yet Therum, I insist that you do.
I have more than five albums to recommend, but I'm kind of annoying in that sense, and as such I'll just list five off the apex of my cranium:
The Doors - Best of. (Preferably the fairly recent deluxe one, as it has more tracks. The more, the merrier as they say. But they have loads of greatest hits albums. If you want an original studio album by them, I say start at the beginning; the self-titled debut is wonderful) Morrison's voice is ever changing, from silky smooth to gravelly shouting. He, Manzarek, Krieger and Densmore are masters of their art.
Joseph Arthur - Come to Where I'm From. Frankly, I love this guy. I finally saw him live the other day (no small feat considering I live in ol' Blighty) and he blew me away. There's so much emotion in his songs. The most recent album is with a band named the Lonely Astronauts, and kind of lacks the rawness of the older ones. Also, try Redemption's Son; rather more soft, but it's the album that got me started.
Beck - Odelay. Okay, so generally speaking, most people would think of Odelay if you mention Beck to them, as well... it's his most well-known album. It's rather more accessible than the others, and sticks to a more mainstream genre. This does not make it 'better', just... a better beginning for someone yet to be versed. Beck tends to experiment a lot with his albums, so some might not be for you, but I'm loving this guy at the moment. Guero and Mellow Gold are also highly recommended.
Snow Patrol - Final Straw. A truly wonderful album. I'm not really sure what to say about this one, but I really do love it. Tugs at the heartstrings a tad at times, but this just increases the quality of the piece. The lead singer's hint of an Irish accent in his voice really adds to it too. The two earlier albums are much more uptempo, and the most recent is a bit heavier. The latter, Eyes Open, is great though.
Ian Dury and the Blockheads - Reasons to be Cheerful. Okay, so this is technically another greatest hits album, but has to be included as it includes some rather hard-to-find material from the late Dury, such as Spasticus Autisticus. Yes, I know what you're thinking of a song with a title like that, but don't. Admittedly, the song was banned here in the UK, but this was rescinded when the censors realised the song was a satirical take on how society treats people, and that Dury himself was crippled by polio. Very clever songs and very funny songs, Ian was a genius.
So there's my five. But my CD player has just switched discs and the debut album by Guillemots has started. Just rediscovered this and it is brilliant. Listen.