I have to agree that SharpDX is the better choice. Namely because SlimDX is a C# wrapper library that links to the C++ built DirectX libraries and SharpDX is actually a rebuild of the DirectX libraries in Managed C# code (See the SharpDX website for better explanation). Both the SlimDX and SharpDX projects are lead by the same developer, and as such SharpDX gets all of the attention now while SlimDX I believe has been all but completely abandoned. Also from my understanding SlimDX is for Direct X 9 or 10 only and does not support Direct X 11 (I could be wrong on that one). AFAIK Tutorials for both are still lacking and or non existent, however they should be growing in popularity and hopefully we should be seeing better resources coming along soon enough. The good part of SharpDX is that is done come with quite a range of demo apps and source code that you can reverse engineer. Taking what they show you and cross referencing against Direct X C++ information can get you to the answers you are looking for in most cases. If you take this approach do be sure that you have a firm grasp on programming basics, theory and the core differences between C++ and C#.
Hmm, no different guys, although the SharpDX guy did pitch some of the ideas behind SharpDX to the SlimDX devs. Also, SlimDX supported D3D11 fully, It's the "Windows Store"/Win8 (and D3D 11.1) they didn't have any interest in supporting.
To the OP, like Dan said, the D3D API exposed in SharpDX is practically 1 to 1, so if you haven't MSDN is usually a good go-by for Direct3D documentation and programming references