Hi,
Computer science engineering is ever green branch, which has plenty of job opportunities.  The competition for job or placement is not that tough.
But , aerospace engineering is upcoming sector,  mostly all placement and job opportunities available only after clearing gate for public sector.  Private sector only few offer aerospace job to btech freshers.
If you are truly passionate about aerospace then go for it or else better choose computer science.

Aerospace engineering if done from indian Institute of space science and technology, then it is the best as you get to go into ISRO directly. You can get admission into this college with jee main score and cutoffs are very high at about 97 percentile plus for general category. Aerospace engineering can fetch you jobs at the airports as engineer. The salary depends on the airline you join.
Computer science is very high in scope currently. Although the growth is stagnated. Salaries up to 2-4 lpa is expected for a computer engineer. Job availability is higher than aerospace. It all depends on your interests too. If you are interested in aerospace engineering, then go for it. You will find a way to get good salaries. In IT industry,  the growth factor is a little troubling as there is but throat competition for every promotion. It gets difficult after a certain level to progress ahead.