We did chocolate cake/chocolate custard/whipped cream frosting most recently for my chocolate-loving teen. The whipped cream lightens it up and prevents from being too rich.
I haven’t had a bad combo, but I can vouch for the marble/custard/whipped icing above.
We have also done that combo with cannoli filling instead of vanilla custard. The yellow cake with strawberry filling and whipped icing was also a hit.