Linux with Best User Interface

One person's best is another person's worst. If you want it to look just like Windows 7 - use Windows 7. Otherwise, only you can know what you deem to be "best". Try a few distros and see what you think.

What I'm saying is that the interface is up to you. For Fedora alone you can choose between GNOME 3 (What your brother has), KDE, XFCE and LXDE. There are countless ways to customise each, and a who lot more out there.

http://en.wikipedia.org/wiki/Desktop_environment

Desktop environments are like masks and Linux is like people at a masked ball. We can interchange masks, swap them around and (outwardly) look the same. On the inside we are different people, the same species, but different people. We are not different enough that organs and blood cannot be transplated between us, but it does not always work. What you are asking us is to tell you what person (Linux) looks like the Windows mask.

Because you have said the above I recommend Sabayon or Debian. You can freely change the masks for Sabayon or any Linux for that matter. Just find themes online (google them) for your chosen distribution and install them.

KDE feels slow to me... crazy loading times.

Sounds to me like the OP really wants the eye candy, in which case Enlightenment has to be a contender.

The big point that amdfangirl is making is that pretty much any flavour of Linux can run any window manager you want. You need to escape MS thinking on this and look at it more like the days of Dos and Windows 3.x. In this case Linux core is DOS, the Window manager the GUI that sits on top of it, more like Win 3.x or OS/2 did back in the day.

Having got that mindset you can see that any distro can be made to look just how you want. You want Ubuntu as you like the package management but also want eye-candy? Install default Ubuntu and then install Enlightenment. Like Fedora but want a lighter GUI? Install Fluxbox or LXDE.

At one stage when I was working at a Unix shop we had 10+ flavours of Unix, a couple of flavours of Linux and about 50 different Window managers from the closed worlds of SGI through to the then suggested saviour of the desktop, CDE. Ultimately most people tried a few and then went with something light like TWM as this was early Pentium days, when a 16Mb graphics card was indulgent and 10Mbit network connections were the standard in the office.