Three years ago, Dream Theater released a compilation entitled Greatest Hit (…And 21 Other Pretty Cool Songs). The title refers to the band's 1992 single "Pull Me Under," which hit Number 10 on the Mainstream Rock Track chart that year and actually received some airplay. For a prog rock band – especially one that started in the mid-1980s– that's an amazing feat. They never repeated it, but the band's army of fans couldn't care less. They probably even prefer it that way. Led by guitar god John Petrucci, Dream Theater play to gigantic crowds that regard them as the only band that matters. Beloved drummer Mike Portnoy left the band in 2010, but the band soldiered on and are releasing a new LP in September. 

For some rock fans, prog rock started in the late 1960s with King Crimson and ended in the early 1980s when Yes, Genesis and Rush all started scoring massive radio hits with short, poppy songs. While the genre certainly peaked in popularity during that time, the genre has never really gone away – or stopped evolving. The Mars Volta may not be "prog" in the ultra-strict Tales From Topographic Oceans sense of the word, but it's impossible to listen to the Omar Rodriquez-Lopez-led band and not hear just how much the genre has influenced them – or the length of their songs. They are also one of the few prog bands with an extremely young audience, who probably wouldn't know a Robert Fripp if he fell on them. 

If Mars Volta defines prog rock for the last decade, Tool defines 1990s prog. The group probably can be more accurately defined as prog-metal, and they retain a gigantic cult following despite their minimal output. The group has been together for 21 years, but in that time they've only released four LPs. They don't have anything that even resembles a hit single, but they pack arenas and headline festivals every time they hit the road. The band toured last year and were talking about a new LP, but the group's leader Maynard Kennean is devoting much of this year to his side project A Perfect Circle. 

Emerson, Lake and Palmer get a bad rap. Some critics (particularly punk rock fans) say their name makes them sound more like a law firm than a rock band, and that they signified everything wrong with the bloated arena rock of the late 1970s. People say they single-handedly inspired the punk revolution. That's an awful lot to pin on a single rock group, and even if that's true – it's quite the accomplishment. Haters aside, it's hard to deny songs like "Lucky Man," "Karn Evil 9" and their rendition of "Fanfare For The Common Man." The group began as a prog-rock supergroup featuring members of the Nice (Emerson), King Crimson (Lake) and Atomic Rooster (Palmer). They merged classical music with prog and were packing arenas by the mid-1970s, but times changed and they quickly grew to despise one another. There have been periodic reunions over the years, and just last year they played a one-off gig. 

Yes is the longest running soap opera in prog rock history. Alliances within the band are constantly shifting and members come and go in what seems like a revolving door. At the center is bassist Chris Squire, the only man to appear in every incarnation of the band – though even he wasn't a part of the late Eighties Yes splinter group Anderson Bruford Wakeman Howe. It's all very convoluted. Anyway, it's beyond dispute that the group's early Seventies output stands out as some of the greatest moments in prog history – particularly 1972's Close To The Edge and 1971's Fragile. They had a huge comeback in 1983 with "Owner Of A Lonely Heart," but since then it's been mostly downhill. In recent years, they replaced original lead singer Jon Anderson with the frontman of a Yes cover band. He now tours with former Yes keyboardist Rick Wakeman. It's almost too complicated to fully explain or even understand. Just put on "Close To The Edge" and transport yourself back to a simpler time. 

The big bang of prog rock was King Crimson's 1969 debut LP In the Court of the Crimson King. Months after the record was released, the original line-up dissolved and Crimson has existed in countless permutations ever since. The only constant member is Robert Fripp, though he seems to have lost interest in the band and they haven't played in a few years. "As long as I felt it necessary for KC music to enter the world, I was prepared to take on pretty much whatever nonsense came with it," Fripp wrote in a December 2010 diary entry. "Today, there are greater necessities for me than pulling new KC music from the air & touring the world to present it to ears that would rather hear an older repertoire (which is pretty fab, may we note). Live KC music of any period would have value, but I doubt it would shape the contemporary musical debate. A grief of expectations, conventionality, conflicting demands – a younger Fripp would have dealt with it, and suffered. An older Fripp chooses his suffering more carefully." Hey Robert, here's an idea – reunite the original line-up for one final concert. If you're sick of the band, bring the whole thing full circle and then pull the plug. 

In the early 19th century, Jethro Tull invented the seed-drill, effectively giving birth to modern agriculture. About 270 years later, a British band named Jethro Tull released Aqualung, effectively giving birth to flute-driven prog rock as a commercial juggernaut. They never released an album as successful, but it's not for lack of trying. The band has 23 albums under their belt, and they tour constantly. Their 1987 LP Crest of a Knave won the Grammy Award for Best Hard Rock/Metal Performance Vocal or Instrumental, beating out Metallica's …And Justice For All. Jethro Tull have endured a lot of mockery for this, but clearly the Grammys are the villains of this story. The Tull had no anti-Metallica agenda, and they didn't select their Grammy category. Leave them alone. 

Genesis break many rules of rock & roll. Bands aren't supposed to get more and more popular as as the decades go by. They aren't supposed to sell more records after their ultra-charismatic frontman leaves for a solo career. The drummer isn't supposed to effortlessly take over as singer. But Genesis are trailblazers. The early records from their Peter Gabriel days – like Foxtrot and The Lamb Lies Down On Broadway – give them endless credibility in prog community. By the 1980s, Phil Collins had taken over and they were churning out pop songs like "Illegal Alien" and "In Too Deep." They were also headlining stadiums all over the world. It was a weird time. Phil quit after the 1992 We Can't Dance Tour, and replacement singer Ray Wilson never connected with audiences. The Phil Collins line-up toured in 2007, but Peter Gabriel stubbornly refuses to commit to a tour.  In 2005, he called a band meeting and almost agreed to a reunion – but he got cold feet. It's very, very frustrating for the massive Genesis fan community. 

You gotta hand it to Bob Geldof. By 2005 it seemed impossible to imagine the classic line-up of Pink Floyd ever standing on the same stage. It had been 24 years since Roger Waters had shared a stage with David Gilmour. In that time, there were lawsuits over the name rights, endless squabbles in the press and seemingly no chance of a reunion. Geldof can be convincing, and after much back and forth he got the four men to agree to it. Their four-song set was absolutely glorious, and just three years later keyboardist Richard Wright died – forever ruling out a full reunion. You hear that, Peter Gabriel? If you wait too long, it becomes too late. 

Well, this poll wasn't even close. Rush won in a landslide – but this couldn't come as any surprise. The Canadian trio have perhaps the most intense and enthusiastic fan community in all of rock. The band deserves such commitment. While most of their peers have fallen apart due to greed or laziness, Rush has maintained the same line-up since 1975 and their concerts are as spellbinding as they ever were. It's also beyond dispute that Neil Peart is the greatest drummer on the planet. They just wrapped up an epic tour where they played Moving Pictures straight through, and are working on a new album. Here's hoping that they bust out 2112 the next time out. It's the only way to top that last tour.