JU is the best option among IIIT Delhi and IIEST for CSE. Although JU is way better than IIEST in CSE placements, it is slightly behind IIIT Delhi. IIIT-D has slightly better CSE placements. But JU offers an excellent ROI which makes it the most favourable option among these colleges. Moreover, its faculty is highly experienced and learned with many Ph.D. holders in just a single department. Here are some other reasons why you should consider joining JU

• It's the only University or Institute in India to host an international cricket team.
• The institute has excellent sports facilities including a swimming pool, a tennis court, and an artificial wall for mountaineering and hiking.
• The institute has an active club culture with many academically and athletically oriented clubs. Some of the unique clubs are the Science Club, Mountaineering and Hiking Club, Photography, Debate Society, and many more.
• It was the first institute to receive TEQIP funding from the World Bank in India
• It is an Innovation University and so is eligible for more monetary grants. 
• 6. It has more centers of excellence in research than the number of UG branches offered at IIIT-D or IIEST.
• It's expected to become the center of research in Eastern India
• The ROI offered is high. Its fees are as low as INR 10,000 for the first year, while the highest package offered last year was INR 1.8 CPA.

All these points sum up the fact that JU is an excellent choice for a CSE degree.

NIT Silchar is a leading and highly reputed institution, as it is the oldest one. NIT Silchar has better faculties, placement support, a resourceful atmosphere, and infrastructure, but the weather conditions are very bad. If you want to explore North India, then you can opt for NIT Patna; otherwise, you can go with the option of NIT Silchar for a better future.

It’s illogical to compare two programs as the choice of branches depends on individual preferences. I will share the limited knowledge I possess for IIT Hyderabad CSE.

• IIT Hyderabad CSE department is very dynamic and rigorous. 
• The CS department has excellent professors that are very learned and experienced.
• The student crowd comprised good quality students most of them being top rankers. There is tough competition between peers maintaining the dynamic academic environment.
• The average package for CSE in IIT Hyderabad is the highest of all the other branches, with many international offers too.
• As far as higher studies are concerned, if you plan to do an MS abroad, every year a lot of students get admitted to highly reputed foreign universities like Stanford, UIUC, Georgia tech, and ETH Zurich.

Since I have no information on IIT Guwahati, I recommend you contact a senior and discuss basic details.

B.Tech in AI(Artificial Intelligence)

This course is somewhat similar to CSE except that you’ll be mainly studying courses on machine learning and AI. Students of this program have to be proficient in Maths, ML, DL, etc. These courses are compulsory and you will be assigned projects on the same topics.

B.Tech in CSE

Under this program, you will be studying CSE subjects like databases, operating systems, networks, computer architecture, etc. IIT Hyderabad’s fractal system will let you take AI subjects and work on areas of ML and AI as well. So you are free to choose your research area.

Ultimately, you should determine what interests you and then only decide what to take. It’s better to research everything before making the final decision.

Artificial Intelligence is a specialization that is expected to be in high demand in the near future and its scope is yet to be determined. I don’t think it’s safe to go for a newly launched field that too from a new IIT. The program and institution both lack the necessary credibility. I would recommend you go for a general branch at a new IIT, a specialization like AI from a well-reputed institute. There are many factors one should consider like faculty, subject content, etc before going for a new specialization. 

Mechanical at IIT Guwahati on the other hand is a very safe choice considering the high credibility of the long-standing Institute.