She is leaving it up to me, the thing is, its my first time making a strawberry filled cake (I usually only bake for my kids b-days) and I don't want flavors to clash.

In that case the first thing I'd think about is what cake you have made, frosted or covered in fondant, or whipped cream, does your friend like the most, and go for that. Vanilla cake with strawberry filling will go with all three quite nicely.

That said, if it was me, I'd go for the whipped cream and decorate the cake top and sides with more strawberries, and add shaved chocolate to finish. I'd also have a big bowl of lightly sugared strawberries on the table for guests to help themselves as many guests like to spoon extra strawberries onto their piece of cake.

But.... that would only be if the whipped cream covered cake was to be eaten right away, and of course, if the cake is not the typical decorated cake. If you're going to decorate it like your usual cakes, you'd be better off using fondant or buttercream.