AI don't think you can go wrong either way or you could do both!
Im only making a few, since its my first time. I've made a chocolate buttercream frosting before, and I know it turns out really well. But Im just not very familiar with the taste of ganache, and not sure how firm it will be when its cold?!
AJust change the ratio of chocolate to cream to change the consistency of your ganache. You might need to play a little depending on the Cocoa solids of your chocolate. I use Callebaut couverture, for the dark choc a ratio of 2:1 choc:cream gives ganache for truffles you can cut and dip; a ratio of 1:1 choc:cream is better for piping.