Some dude.

All but like, 2 of the Vizard were ex shinigami captains.

They have all mastered their Hollow powers aswell.

For instance, when Shinji turned up, he was pwning Grimmjow like crazy, so badly Grimmjow was about to release his Zampakto.

Now, lets not forget that, Shinji was fighting as a hollow.
And Grimmjow as an unreleased Espada.
Shinji didnt even release his Shiki, let alone his Bankai.

Basically. Vizard, would totally pwn the Espada.