i got offer from both university Aston and Essex for MBA full time program , i confusing which one i should take .
especially my goal for studying to extend my business to increasing our performance .

please advise me ?

Educationally these will be quite adequate, but why not attend a better programme with better students? Then you'd learn more. 

Focus on your goals. Why these schools? Even something like Durham or Imperial, both ranked in the FT, would be better in terms of most indicators.