Number five I would think is the cheapest out of the list. It Acer I have tried Acer they are not so good. You want one that will last you. Not always fixing you need to use. Check battery life aswell.
I am an engineering student and using a Lenovo laptop it works good and I'm reliable with it can run all of engineering programs and the charge life is good too.
I say a tablet is cheaper. Even Samsung is good but cheaper. Some tablets you can use with a keyboard. You could have a couple instead of just one laptop. Especially laptops are expensive like everything.
There are so many laptops that engineering students can choose from. To name a few are the following: Alienware m15 R4, MacBook Pro, Dell XPS 15, Dell G5 15 SE, and so on.