Hi,

Both of these colleges are not top tier MBA colleges but are decent ones.

If you are aiming for a full time MBA course, St. Hopkins would be a better option to go for. The faculty, opportunities and exposure is much better. The fees of both the institutes is almost same (close to four lakh rupees). Students at Hopkins get to go abroad 2 times in a span of 2 years to study(international exposure) and the placements are impressive. The average package is around 4-5 lakhs per annum. 

GEMS is an institute with no permanent faculty. It is ideal for people who want to study while working simultaneously. They have weekend programmes too. Placements are average.

All the best!