If you are a general category student, you will need an AIR of around 1000 in order to get admission in B.Arch at NIT Calicut. This means you will need to have a rank of around 300 in JEE Mains Paper 2. 

Here is the cutoff for B.Arch at NIT Calicut in recent years. 

My sister appeared for JEE Mains paper-2 in 2013 and scored 228, his rank was somewhat around 5000. She got NIT-B in the 3rd round of counseling itself.

Firstly a hearty congratulations to you for scoring a good rank in JEE Main. However, it is quite difficult to get a seat at SPA Delhi in this rank. The 2nd best option can be SPA Bhopal. Moreover, SPA Vijayawada is relatively newer and cannot be trusted.

I have friends studying at both Bhopal and Vijayawada, from what I've heard, Bhopal is a better option. SPAs are purely design institutes and thus the exposure would be greater. 

Since your chances at SPA D are quite on edge, you can instead look for the following colleges in order of preference: 

NIT Nagpur> NIT Bhopal> SPA Bhopal> NIT Jaipur> SPA Vijayawada and so on.

If you want to go for NITs, choose the one with better infrastructure, weather, and a diverse crowd. There are many other good institutes as well but do your proper research and take the right decision for yourself. 

My friend did his B. Arch from BIT Mesra, so I can give you a brief idea about the course.

Architecture depends on your vision, on your projection, and how you see the world. Therefore, college views could differ. Architecture is not like maths which would be the same throughout the world, it is designing and depends on how you can plan your thoughts.

Some of the striking features of BIT-Mesra (Architecture) are as follows.

• BIT-Mesra has a state-of-art course structure. This may not sound important but most of the top universities look at the course structure for Masters.
• BIT-Mesra has great faculty. Most of them get an offer from the most prestigious colleges around the world.
• B.I.T. gives a strong software and structural base to students. They are successful in making you think economically too, very important in a country like India.
• There is a good balance between contemporary architecture and traditional architecture.
• Alumni Network: The Alumni network at BIT-Mesra is strong as well as global. In college, electives like Architectural Journalism, Photography, Conservation, and Urban Planning are good to have and though, they are only a few among so many, it gives you an idea of different fields you can aim for from B.Arch.
• Placements or Job-Scenarios: On-campus training and placements isn't a very happening scene in BIT-M, though there are amazing placement stats among other departments. But things are different for architecture and they have an effective system builtin in the course structure including internships in the final semester. This also happened because students generally have internships finalized (through personal emails) much before the Career Fair starts. 
• Co-curricular: Being a nationally recognized school, great co-curricular activities are happening in the college regularly. These co-curricular lead to the personal growth of an individual and architecture comes out as the winner in many activities and competitions. Great workshops are organized throughout the year at the institute.

Going by the above factors, it is safe to say that BIT Mesra is a good option for pursuing a degree in Architecture.

Manipal University is ranked 19 for Architecture by India Today 2020. The B.Arch program is offered by the Manipal school of architecture and planning (MSAP). It is approved by the Council of Architecture (CoA).

Admission criteria:

The admission criteria are the same as the other courses at MU like engineering and management courses.

• Entrance test (MET)

• Online counseling

• Direct admission (for meritorious students)

There are two eligibility criteria for B.Arch admission.

• The 1st one is the academic marks, the candidates securing 10+2 science with 50% marks from any recognized university are able to apply for this particular program.

• The 2nd one is the entrance examination score of both MET and NATA (National aptitude test in architecture) score.

BArch from Manipal costs almost 18.5 lakhs for 5 years. There are 40 total seats for BArch at Manipal University.

Faculty: The faculty members are well qualified and have years of experience in the field. The department also invites visiting faculties.

Course curriculum:

The course work for B.Arch. rigorous and includes various tests, assignments, and exams. Learning methods such as block models, sketches, PBL is employed for teaching.

Placement:

There are not many placement opportunities for B.Arch at Manipal University. But the university has an internship program, in that period of time the students can learn more practical and technical skills in both architecture and design.

• A median salary of 2 LPA is offered to the B.Arch students.

• The major recruiters for architecture students at Manipal are BirlaSoft, Dell, Amazon, Accenture, etc.

Speaking strictly from the placement perspective, the BArch program at Manipal University is average.