DraftKings vs FanDuel detailed comparison after using both

Been bouncing between both apps this month and really trying to track which one actually gives more value overall. I feel like the promos are usually neck and neck, but one always has slightly better odds for the underdogs on NBA games, while the other pushes those big boosts for parlays. Interface-wise, both have quirks that drive me nuts but nothing majorly game-breaking.

Noticed the slots have way different RTPs too, though the info is buried unless you really dig. Anyone else find that managing your play on both helps your bankroll last, or is it better just to stick to one and know it inside out?