UPES

First of all, it is good to know that you are opting for B. Tech in Aerospace Engineering. Second, UPES is one of the best choices to get a degree in this outstanding engineering field. Now coming to your question, to take admission in UPES, you can appear for UPSEAT if you have secured minimum 60% marks at Higher & Senior Secondary level (class 10th & class 12th) or minimum 60% aggregate in Physics, Chemistry & Mathematics at Senior Secondary level (12th).
UPES also offers admission through Board Merit / JEE Mains Score. 20% of seats are available for those taking admission through their JEE score. There is a total of 60 seats in B. Tech in Aerospace Engineering.
And as you have mentioned that your marks are above 80%, you can easily apply for B. Tech in Aerospace Engineering at UPES. All the best.

I would say UPES without a doubt is better in placements for MBA students, especially if you are a mechanical graduate. It has 96% placements in last 3 years, and is consistently ranked amongst the best universities for MBA placements. Furthermore, UPES also has consistency in MBA placements and fortune 500 companies regularly recruit MBA students from UPES. Not only this, UPES has many specialised MBA programs that you can pursue which are not available in other universities. These MBA specializations have immense scope and the placement record is also top-tier. The overall package offered to MBA students in UPES is also higher. A lot of fortune 500 brands that specialize in mechanical engineering recruit MBA students from UPES. Brands like Volvo, Eicher, Maersk, Adani, and others hire students from UPES. So, I will suggest you go pursue MBA in UPES if you want a good placement. Also, it is in Dehradun, which is nice place to study and the weather is also really good.