The best laptop operating system 2015

Rather than asking which is the best laptop operating system 2015, being an Open Source fan I would ask, what is the best Linux operating system for laptops in 2015 :-).

I see number of laptop users are migrated to Tab, how ever Engineering students and developers have to use lap top with a really helpful operating system to complete their day today tasks more efficiently. I would rank the most popular OS useful for your laptops here.

#1. Ubuntu
In my view, Ubuntu would be standing on the top of this list on 2015 too since there are no peers for them at this moment. It is so easy for a newbie Linux user (even for first time Computer users including children and elders).

#2. CentOS Desktop
Very stable Linux Operating System, originated from Red Hat Linux server world, less attractive if you are comparing seeing the color of the menu bar or number of wallpapers, how ever for engineering or development purposes, this is more efficient in my view.

#3. Windows 7
Seriously, Windows is still holding its charm, very powerful and stable, I love Windows 7 than any other Windows series because of its simplicity and speed.

Which OS are you using in your laptop? Share your opinions and views!
I used windows xp for long time and now using windows 7. Did not get a chance to try windows 8