Having friends in both the institutes, I might be able to help you with the question. Welingkar, Mumbai, and PUMBA are two opposite colleges, and comparing them is the same as comparing the North and South directions.

• Welingkar has a cut-off of 99 for MMS and in the course of PGDM, the cutoff is above 70 percentile which should be scored in CET.
• If scored above 70 percentile, a person would be called for GD and PI.
• On the other hand, PUMBA in CET has a quite good cut-off ranging from about 94-95 percentile.
• The campus is quite good also as it offers the whole Pune University Campus to sit and have fun in.
• Along with the cut-off and campus, It's also better in terms of ROI.

A year drop will not be a problem. Assuming these pros and cons, decide the University that best suits you.