The brightest orange rose in my garden is Kordes' Brillant, but it's rather difficult to find, and it doesn't bloom that often.
Rose (Rosa 'Kordes' Brillant')
For a vivid orange on a rose bush that's almost always covered in blooms, try Marmalade Skies:
Rose (Rosa 'Marmalade Skies')
For a lighter orange, the same color as orange juice, try Vavoom:
Rose (Rosa 'Vavoom')
