What should we play for our orchestra ensemble?

My friends and I have formed an ensemble for an orchestra competition. We have four violins (two firsts and two seconds), a viola, and a cello. We are all in 8th grade, but I believe we are rather advanced. Last year, all of us (except one) played Brandenburg Co. 3 (mv 1) by Bach and recieved top marks. This year, we would like to play something more challenging, excluding the other two movements, but we are not to sure of what to play. Do you have any suggestions?