What type of pedal you should add to your collection is completely dependent on what tone you're going for. One of the most long running debates dealing with electric guitar are as extensive and continually on going as guitar pedals and effects. It has become an industry unto its self. Players still use everything from beat up vintage amps with built-in reverb and tremolo to brand-new modeling technology.
From single pedals designed to enhance your guitar's tone to otherworldly designs that create sounds never heard before, there are enough types, brands, and formats to keep every guitarist's gear addiction satiated for a very long time to come.