See from the perspective of engineering, I would say you must have a good laptop with SSD and graphics card as in Mechanical Engineering there are simulation and designing of mechanical systems which when run in low space devices usually crash or it don't work efficiently. The systems hangs a lot. So if you have the money to buy a good device then you should try to get a laptop with a good HDD and SSD support and if possible get a graphics card. This will help you to enhance your experience of doing 3-D designs and simulations. Also you should try to get i5 or i7 processor if possible and obviously as per your budget.

Ipad will not be that much useful until and unless you need to make digital notes and read pdf's etc. But having a efficient laptop is always important.

To know more about Mechanical engineering visit the link below:

https://www.careers360.com/courses/mechanical-engineering-course

I hope this answer helps. All the very best for your future endeavors!