DirectX 11 doesn't have better graphics (probably confused by the bullshit propoganda Microsoft spread). It is an improved API with more feature, possibly with the potential to be faster, but it's based on the user to provide graphics. It doesn't magically fix non-antialiased lines or make a blocky arc way smooth. It can HELP those situations however but it doesn't do that just because you're using DX 11.
Lots of changes (for Direct3D) have happened since DirectX 9; DGXI, new shader models, COMS and like computerquip mentioned, changes to the pipeline. If you learn DX9, you'll have to remove old habits once adjusting to newer versions of the API. Then again, I know people are going to disagree with me over this, though it wouldn't hurt using DX10.
Despite I'm a DX lover, I'm sure you may want to put OpenGL in the topic.
Due to the support/updates from Gfx Cards Manufacturers, i'd say DX11.
About ease of use, DX9 or OpenGL.
DX11 is becoming the "New DX standard" (Just as DX9 was, why not using DX8? Because DX9 has more/better/newer features).
But DX9 has been used more and more time, so it's easier for you to learn to use DX9.
OpenGL has always used the same functions (even if there's newer OpenGL versions now, which, again, bring you more/better/newer features).
Just because they stop adding updates doesn't mean people are going to stop using it.
My school still uses winXP to this date.
I do agree. But, all of the schools I have gone to still have WinXP. It is just cheaper computers they go to save money.
My last school had these in their computer lab:
a lot of Dell Latitude C610's (from about 2000ish)
one Toshiba Satellite 4200 or 4600 Pro (from around 1999)
^These originally came w/ Win2k or Win98
a few Dell Dimension 3000's (from around 2004) actually I have one of those, but I don't use it.
and other old computers that have WinXP
@Foxefde Why not? One of the only reasons developers are still clinging onto DX9 is due to it being the API of the current gen Xbox. You may argue that DX10 was pointless and should have been released with 11, though the reason I am using it is since it's minimum supported client OS is Vista, and it comprises of less features (that are currently unecessary to me) and a simpler interface (in my opinion) than DX11. I don't need it.