It all depends on your personal preferences and what appeals to you the most. However, if none of these two branches piques your attention, then definitely mechanical engineering in PEC is the way to go. 

• Mechanical is often favored over Aerospace in terms of placement, faculty, or any other criterion.

• Mechanical is an evergreen branch, as they claim, and they call it that for a reason. 
• It is in high demand. All industries will need the mind of a mechanical engineer today and forever.

It would be advised that mechanical is always a better choice than aerospace. You can choose to go for Mechanical engineering without giving it much thought and discussion.

Both the colleges, BIT Mesra and NIT Raipur are two profound colleges of the nation but comparing them based on different branches is not justified.

Talking about the mechanical and computer science branch, the scope of computer science is the higher and mechanical branches.

Choosing between the two, opt for NIT Raipur, CSE branch due to the scope of the particular domain.

Having friends in both the colleges, I can say that MNIT Jaipur and IIIT Lucknow are equally good in their own ways. If you get a chance in any of these colleges, go for it.

Apart from getting admission in any one of either the only thing which would give you trouble is which field to choose? But, I would like to say that whatever field you choose, if you work hard and be honest with your studies you will land in a better place.

• But answering your question with rank 11803 in the JEE Main; I would like to say that MNIT Jaipur is a much better college than IIIT Lucknow.
• If you ask me, nowadays the trend and placement of MNIT Jaipur are on par. But, if you are really interested in CSE then definitely look for CSE or IT in well-established IIITs.
• And with the rank of 11803, you might have a chance to get into old IIITs or TIER 2 NITs.

And talking about IIIT Lucknow, Their campus just started functioning in 2020. Earlier IIIT Lucknow runs from IIIT Allahabad campus.

Further, getting a job in core trade is very difficult to go to IIIT Lucknow but do check the infrastructure and previous year placement record of IIIT otherwise join MNIT Jaipur in mechanical without any second thought.

One of my close friends graduated from BVM and my sister was in LD. Based on their reviews BVM is a way better option for mechanical engineers compared to LD Engineering College. The reason behind this is, it is one of the oldest colleges in Gujarat. Some more significant points which will make you drift towards BVM includes:

• The faculty members in BVM are highly educated and cooperative.
• The lab facilities at BVM are great. Much better than LD.
• VV Nagar is the educational hub of Gujarat, hence it is the best place to focus on your studies.

Here are some details about the two colleges which might help you to make a precise decision:

Both the colleges are great, but It is suggested you go for BVM among the two. Because a good environment is necessary to concentrate on studies.

There are many things to consider while choosing a college such as placements, location, branch, choice, your expectations after 4 years of engineering life, etc.

If you have a liking for a particular branch then go to that college all things considered. Being a student of MNIT myself, I can say that, if you are only concerned about placements then MNIT Jaipur will prove to be a better choice.

The following data comparing the placements at both institutes will hopefully give you better clarity.

However, if you are thinking of branch change after entering the college then MNIT Jaipur does not provide that option while PEC Chandigarh offers that option. So choose one according to what matters more to you.