Having a friend who is a student of NITA and attended the counseling of AKTU I think I might be able to answer your question.

He was in a similar situation as you are in right now. His UPTU rank was around 2800 and his JEE Main rank was around 33000.

• According to some research I did, I think NIT Agartala is much better than IET Lucknow in terms of both core and CSE/ IT branches.
• NIT Agartala has been ranked as the top 75th engineering college by NIRF.
• In terms of CSE/ IT branches, the placement scenario at NIT Agartala is much better compared to IET Lucknow.
• In terms of core branches, the placement record is also very good.
• The average package is around 5 to 6 lakh per annum in core branches.
• The top companies that recruit students from IET Lucknow include Byju's, Unacademy, Airtel, Idea, BSNL, Wipro, TCS Digital, TCS Ninja, etc.
• The top companies that recruit students from NIT Agartala are Google, Microsoft, and many service-based IT companies.

But if you are a resident of Uttar Pradesh and want to study nearby your location then you can go for IET Lucknow.

Considering these two institutes, as mentioned in the question, NIT Silchar is better than NIT Agartala, without any doubt. Followings are the reason why this institute is considered as best.

Infrastructure

• NIT Silchar is on the list of oldest NITs in India. It is also among the group of 8 RECs.
• It has a well-organized infrastructure with 680 acres campus area with 3 girls hostel, 6 boys hostel, and 1 marriage quarter.
• This institute also has the country’s largest digital library. Besides, college administration also provides outstanding sports facilities two each of its students.
• The campus internet facility is just awesome.

Communication

• If you consider communication, then NIT Silchar is in a far better position than NIT Agartala.
• Additionally, the opening and closing rank of this institute is also healthier than the other one.

Academics and Research

• NIT Silchar provides good academics and research facilities to its scholars.
• This institute's research cell assists the students with abundant opportunities to discover things related to their respective research subjects.

Placement

• It is one of the important points for an institute to judge.
• In the 2016-2017 sessions, approximately 60+ companies came here to hire students from campus recruitment.
• Every department of this institute provides placement, and CSE is the best for getting a job in the on-campus recruitment process.
• Companies like Microsoft, Bharat Electronics, Sap Labs, Oracle, Directi, Power Grid Corporation, Indian oil, Wells Fargo, Indian Oil Corporation mostly come for recruitment.

In the following, a brief overview has been given related to the placement fact of these two institutes:

Thus, it can be mentioned that NIT Silchar has the best institute tag in North East India. This institute also gets a reward from the renowned magazine.

NIT Srinagar is good and if it is discussed in the North East, it is the most excellent. The infrastructure is quite good and the college administration is focused enough to give proper resources to each of its students for their appropriate development. 

The campus is approximately 375 acres, with green lushes all around. Faculty members are also outstanding and friendly. Besides, placement statistics are really rising every year, which is good for this institute.

In the following, a brief overview has been given of these three NITs mentioned in the question.

NIT Srinagar is growing at an excellent pace, and it will reach the top level shortly. It would be a renowned institute in India. Thereby, you need not to take admission in the North East NITs by thinking NIT Srinagar as a bad institute.

Although NIT Agarta holds a bigger brand name, it is still a growing NIT. On the other hand, PEC has an older history of about 100 years and continues to flourish. 

Here are some insights into the PEC according to my friends who completed their B.Tech from there.

• Faculty: PEC has some of the best-experienced faculties and many research scholars. On the other hand, NIT struggles to have enough experienced professors as the NIT is newly established.
• Location: Chandigarh is at advantage any day because of its easy proximity and being an education hub. It is better in terms of facilities and coaching centers too. Whereas, Agartala is at a huge disadvantage due to accessibility and opportunities.
• Quality of students: You can see a huge difference in the cutoff trend of JEE Mains rank for both the colleges. In the case of NIT Agartala, about 50% of the total seats are reserved for home-state candidates in the range of 90k to 1.5 lakh. Whereas the cutoff trend is much lower at PEC with just over 60 K for branches like metallurgy!
• Clubs: You can choose over various clubs at PEC Chandigarh. Theseclubs are well renowned and they have even gained respect in IITs during fests and events.

All in all, it is recommended to choose PEC Chandigarh any day over NIT Agartala. PEC definitely belongs to the league with NIT Surat, Allahabad, and others. However, if the NIT tag is all that you are looking for, then go for NIT Agartala.