It really depends what kind of student life you want, my brother is staying at home and commuting to uni and he loves it, he is still apart of societys and he has saved loads of money while being at home. However if you want to be more independant and develop skills for living on your own you should go to Southhampton, I would say its also easier to meet new people if you live at Uni, living in halls is what I am planning to do. Southhampton is also considered an amazing uni to study Aerospace at, its ranked pretty highly whereas Exeter is still good just ranked lower. I hope this helps, if not unis often have a part of their websites where you can chat to students who currently go there, might be worth doing that to get a better perspective on uni life at each uni.