I'm a second year MBA student and will throw in my 2 cents of advice.
If you are used to having a PC, definitely stick to it. ASUS and Lenovo are the two most common brands for PC's amongst my MBA class.
However, if you are a Mac person you have to options: go back to PC (I wouldn't) or stick to Mac.
I personally prefer Mac, and have had no problems using Mac in b-school. It is true that some software is only compatible with windows, but you can easily install windows in your Mac. Windows runs much better in a MacBook Pro than i've seen it run in any PC. The comparison is particular striking when you run simulations in excel, the Mac is about 10x faster than your average PC.
So my advice is stick to what you like and don't worry too much about "what's best for b-school". If you like Mac, you'll make it work and you won't regret.
Don't get a MacBook Air though.... it may be slow if you have to partition your hard drive to install windows, and tablets are NOT a replacement for laptops.
Hope this helps.
On another note, you guys should check out a site called pymetrics. They are a neuroscience game-based career assessment platform that matches you with industries, companies and ultimately real internship and job opportunities. I found my summer internship through them and thought they were awesome. Wish I had heard about them b4 entering b-school.
https://bit.ly/1JxEviS