Both Kahoot and Quizziz caught my eye. I feel like I would have to get to know my next caseload of students before I decide which one I would pick. I've had highly self-conscious students who would "blow out" if they felt like they weren't answering correctly/quickly/consistently, so I wouldn't want to display names that are placed low on the scoreboard. I've also worked with students who benefited well from the positive praise, so that would definitely help if they could see their name on the screens top 5 like in kahoot.
I definitely will look into MCOEs portal. It really is a wormhole of resources.