Petyr Baelish is currently the Lord Paramount of the Trident
It is the wish of the King's Grace that his loyal councillor Petyr Baelish be rewarded for faithful service to crown and realm. Be it known that Lord Baelish is granted the castle of Harrenhal with all its attendant lands and incomes, there to make his seat and rule henceforth as Lord Paramount of the Trident. Petyr Baelish and his sons and grandsons shall hold and enjoy these honors until the end of time, and all the lords of the Trident shall do him homage as their rightful liege.
-- ACoK Sansa VIII
After Red Wedding, Walder Frey becomes the overlord of the Riverlands
... Two cadet branches of House Frey exist. One holds the seat of Harrenhal and the Lord Paramountcy of the Riverlands the other holds the seat of Riverrun.
-- Game of Thrones Wikia (To be honest, I can't find text reference for this)
Question: Who is the current rightful liege lord of the Riverlands as recognized by the current "Baratheon" crown?