Getting into IIT is a big achievement only if you manage to choose the right branch for yourself.

You should analyze your ambitions and interests in a particular field and determine what you possibly imagine yourself to be doing in 5 years and then make an informed decision. Clarity of goals is extremely necessary to make this crucial decision of choosing a branch.

If you want to enter politics, then your branch hardly matters. 

If you want to become an entrepreneur try to get an idea of the type of company you want to start

Basically, the choice of the branch is strictly a personal preference and cannot be objectively decided.

The quality of Education, the faculty pool, and even the lab facilities offered at both IITs are similar. There might be slight differences as far as internships are concerned because the top companies with coding profiles visit both IITs but the interview process is quite different. 

The main reason for this difference is the location of both institutes. In the case of IIT Kharagpur, recruiters prefer taking a skype interview than personally visiting the campus because of the isolated location of the institute. This plays against the favor of IIT Kharagpur as face-to-face interviews are way better than online interviews. Online interviews do not convey the information and expressions rightly and there is a communication gap.

Companies tend to judge IITs based on rankings which depend on their respective placements. For instance, the same profile and role are offered with a higher package at IIT Kharagpur but with a lower package at other IITs.

While IIT KGP CSE has a wide scope if you have achieved a top JEE Rank and have managed to get into IIT Bombay, go for it.

Both metallurgical and electrical engineering are highly respected fields of study. The choice between them will depend on your personal interests and career goals. The old IITS like Kharagpur and Roorkee has a long-standing legacy in metallurgical engineering, whereas the new IITs like Gandhinagar and Mandi have strong electrical engineering programs. 

However, personally, I feel metallurgy in Kharagpur or Roorkee is a better option than joining EE in newer IITs. Here are a few points that support my stance 

• The exposure, culture, opportunities, peer groups, and overall campus life you will experience at IIT Roorkee cannot be compared to that of newer IITs which are still growing and have a long way to go.
• The branch does matter to a certain extent, but if you look at the bigger picture, the Institute’s brand and opportunities overshadow the drawbacks of a less preferred branch.
• Those who are desperate can always opt for a branch change at the end of the first semester.

Ultimately, the choice between metallurgical engineering at an old IIT and electrical engineering at a new IIT will come down to your personal inclinations and career goals.

Aerospace Engineering can be further divided into four parts 

• Aerodynamics - An extension of fluid mechanics 
• Structures - All about mechanics of materials
• Propulsion - A good base in aerodynamics will help you 
• Controls and dynamics - Mainly used for navigation 

Apart from this there is a lot of Math involved in the curriculum.

The aerospace engineering branches of all the institutes you mentioned give an edge to each other and are equally good. The choice should be based on personal preference, accessibility, campus life, academics, extracurricular activities and placements.

IIT Kharagpur: Pros

• Massive and surreal campus 
• Less academic burden
• Good faculty pool with experienced professors that are easier approachable.
• Companies like Airbus, GE, Honeywell, Altair, Rolls Royce, etc come for placements in the core sector.
• Some of the students go for higher studies in foreign universities like Purdue, Texas A&M, University of Texas, Austin, etc
• IIT KGP offers the Boeing Project wherein a team of 5 fabricates all parts of an Unmanned Aerial Vehicle (UAV). On clearing the selection procedure, you will also be offered a scholarship of about 10k per month for an entire year.
• I am not gonna mention any of the institutional activities (clubs, societies, fests etc.)because I reckon the scenario will be pretty much the same in all the aforementioned colleges.

IIT Kharagpur: Cons 

• It’s not easily accessible to students from Western and Southern States.
• Kharagpur is a town and lacks many amenities apart from its large railway station.
• Mess food is not good at all
• The huge campus delays the time taken to reach the academic area.
• The core companies only select the best students and a major portion of the batch has to go for non-core placements.
• Aerospace Engineering in India has very few job prospects though we expect the scenario to improve a bit 
• You can also apply for off-campus placements at DRDO or ISRO.

Judging a branch solely on the basis of placements is misleading. Yet, most students end up with decent jobs. The best part is that the course curriculum of aerospace engineering is intriguing and keeps you hooked.

The choice of your institute depends on what you are expecting from it. For instance, if you are just after the brand name, then the IIT tag will come to your rescue. However, if you are on the lookout for quality education that will match your requirement to pursue a career in architecture, then SPA is a very good option. The only drawback is that there are no Institute placements and you need to have a good portfolio or Architectural background to get a good job.

If you are after placements, IIT Kharagpur and Roorkee can guarantee you very good packages, sometimes even in crores. The issue with this option is that you will have to first clear JEE Advanced and then AAT, after which only you can get admission.

I have told you the positive and negative implications of both the institute, make a wise decision.