According to the reviews online, among the mentioned three colleges, it is recommended that you go for Poornima University (PU).

Here are some things about PU that makes it better than the others:

• They have an updated academic curriculum, which follows up with the recent industry trends.
• Their examination structure is also modified to match recent trends.
• Their on-campus placements are really good. 
• Students get job offers from reputed companies like HP, Accenture, Wipro, HCL, etc.
• A student with an overall good academic record gets offered a salary package of 9-10 LPA.
• Usually the average salary package offered is 5-6 LPA.
• Their education has a practical approach.
• Seminars, industry visits, etc. also are conducted.
• The facilities and amenities  are well adequate for an educational institution.

PU is considered to be one of the best private universities of Northern India. The placement statistics at the university are much better than most of the colleges and universities in the city. So therefore, between Arya, JNU, and Poornima, PU will be the better choice.