Vengeance Paladin 20
VHuman / Cha 20, Belt of Giant Strength, PAM, Great Weapon Master, Mounted Combatant, Inspiring Leader (Order in which you get the feats is optional, though I'd take PAM first).
High level strategy:
You use "Find Greater Steed" to ride a pegasus. At the start of your adventuring day you give a heroic speech about how much divine vengeance will rain down upon your foes today (which gives everyone and their familiar +25 hp / short rest), and cast Death Ward, which affects you and your pegasus. In battle, you cast Haste, which gets shared to it.
Your pegasus now moves around the battlefield at 540 feet per round using the move action, dash action, and hasted bonus action.