There are many good distributions out there (and yes, Ubuntu is not one of them). I can't comment on a lot of them, but I can tell you this:
Red Hat is a good distro, but not if you want to learn "linux". Using Red Hat will teach you Red Hat, but not much about linux itself.
Debian is not bad, but I personally despise their package management system. It is not as clean is a linux distro should be, but still usable.
I personally use Slackware. I have a six core phenom, 8GB ram, and an nVidia 660, which is an OK graphics card. And I can play many Windows games with great stability and performance, as well as other Windows programs. Tomb Raider 2013, and The Sims 3 both work very well under Slackware.. It is rock solid, and is an old and very stable and very pure distribution. It doesn't get in your way, and is great for beginner and pro alike. I even use it for lamp and web servers, and it works very well. It will support your graphics card very well.
There are two main desktop managers. KDE is an old one, but the current version is bloated and is becoming more windows-ish with a lot of performance robbing bells and whistles. Xfce is also an old one, but is of the get-the-job-done mentality, without the bells and whistles and bloat. I find it similar to Windows XP, in that it isn't bloated like windows 7/8 is.
And NO REGISTRY! What is wrong with Microsoft that after 20 years they just can't figure out how to make the registry reliable and stable? More Windows installs go down the toilet because of registry corruption than anything else. Linux has no registry. Just doesn't need one. No DLL hell either. Linux just works. And is rock stable, never crashes, never needs to be wiped and reinstalled, never needs the registry cleaned, etc. No viruses. No malware. And free.
Why should I pay money for a buggy virus and spyware infected bloated unstable piece of cr*p Windows, when I can get LInux for free that doesn't have all the problems Windows has?
Linux supports a very wide range of hardware, it supports things Windows never will. I have some old bluetooth dongles and an old webcam. They do not work with Windows. They work just fine with Linux.
And although I have 8GB of ram, I use the 32 bit version, because unlike Windows, PAE under linux actually works. 32 bit Windows won't use 4GB, but 32 bit Linux will use 8GB with no problem.
I could go on and on, but you get there idea. These days I just don't have any need for Windows.