Ditto the less butter more sugar PPs. I also use a bit of cream instead of milk and beat the frosting in my stand mixer for 7 minutes or so. It makes the frosting super fluffy and less dense.
I also love this recipe for
White Chocolate Buttercream that I found on a Baker's Chocolate box. But I use, again, less butter and more sugar. To taste, mostly. Strangely, it doesn't taste like white chocolate, it just tastes like a really creamy buttercream. It's fantastic for cupcakes.
Or you can try a boiled milk frosting. Look up Miracle Frosting for recipes.