Although, both the colleges have similar placement records. JMI has a upper hand because of its location - Delhi.

If you want to go for exposure, choose JMI.
If you want to go for Research, choose AMU.

All the Best!

According, to Careers 360 both the colleges have AAAA rating which means very good.

Ratings are based on Placements, Faculty, Cut-offs of national / state level Entrance exams, Accreditation and Reward status and Publication record from Elsevier’s indexing database - Scopus

In NIRF Ranking AMU is in 40th rank and JMI is in 20th position.

Both the colleges are good. You can choose any college according to your preference. 

Good Luck!!