As has been mentioned many of time in other threads, this is a very important and personal process, why would you defer to an anonymous (often cynical) hive mind to make a decision to make like this? 

The two programs you are listing are very different. I would seriously suggest that you take the time to read faculty bios along with their program statements, curriculum sequences (does one favor one thing of interest more than another), etc. That's where you'll find the pros and cons that are in alignment with your interests.

And before you start to list your interest so we can help you decide- don't. It won't do any good.

Neither is particularly strong or well-respected for landscape architecture. If I were you I'd probably take this year to work in some related position, strengthen my portfolio, and try again next year to get into other programs.  If I had to choose between these two AND money were no impediment, then I'd choose RISD because institutionally it's one of the best design schools in the world, it has a lot to offer if you expand your circle outside of your degree program, and the degree has broader name recognition  - though it's also one of the most expensive design schools in the world so if your financial aid offer is lackluster it may not be worth it. 

UMass Amherst is garbage !

RISD is not a strong landscape program !

You would know this if you had done your research before applying !

Why do so many Indian students post these lazy questions ? !

not sure the sweeping generalizations are productive or appropriate.

And on another note: perhaps those are the only options for the op? Granted- they still need to think for themselves...