Advantages: installer provided by Visual Studio, quiet mode, fast installation Disadvantages: package project required, automated creation is complicated, no support for VS 20 Here is a table summarizing features of the discussed approaches.
As you can see, the VSPackage approach gives you the most freedom, but is also hardest to implement.
Please note that VSI and VSIX package installers contain features like displaying EULA, choosing which components to install or localization.
The VS SDK contains tool and project templates discussed in VSIX and VSPackage approaches.
Advantages: zero effort Disadvantages: require experienced users, slows user producitivity, updating controls is not intuitive Visual Studio 2005 SDK contained a VSPackage called Toolbox Control Installer.
This increases chance they will actually purchase your product.
The only trouble with VSI compared to other approaches is invoking a wizard form which cannot be suppressed. Another trouble with VSI is that a digital signature is required in order to get rid of a warning dialog.
Your control will be always installed under "My Controls" tab in the Toolbox, which is not always desirable. VSIX file extensions are associated with Visual Studio so you can simply double-click it or run it via shell.