For me personally, a Rectifier only sounds like a Rectifier through the Recto Standard cab, just because that combination, for me, sounds like what I want a Rectifier to sound like.
Maybe it's just because of the fact that the majority of the Rectifier tones on albums have been recorded with this combination and it is the way I imagine a Rectifier to sound like.
But, in the end it's just a matter of personal preferences. There is no such thing as "the best cab" etc. because people prefer different things. Tone is a highly subjective thing and the tone that defines "the Recto" tone for me, could be a tone that you can't stand.
Mesa makes awesome cabs, the Rectifier Standard is my all-time favourite cab.