.NET CORE 2 Framework standalone vs with .NET Framework

Any recommendation regarding new projects, I m highly interested in building my project in .NET Core 2 and there are two options, 

1. either I select .NET CORE 2 web app which directly target .NET CORE Framework

or

2. I select Web then .NET CORE2 with .NET Framework (MIX)

I m confused between them, The former keeps giving me errors and incompatibility issues in Microsoft design packages dependency 

Package 'Microsoft.Composition 1.0.27' was restored using '.NETPortable,Version=v0.0,Profile=Profile259, .NETFramework,Version=v4.6.1' instead of the project target framework '.NETCoreApp,Version=v2.0'. This package may not be fully compatible with your project.