Sat 2
Also probably BAA want more punters going through Sat 2 too keep the shiny new Wetherspoons and the other concessions busy. Especially now that there are fewer FR international turnarounds during the daytime operating from Sat 2.
And as Carbootking commented Air Berlin ops are spread over Sat 1 and 2 currently as the Domestic Ops have to depart from Sat 2 and this is causing a large amount of Bussing of punters.