Leder's games are something I've slowly come around to appreciating although there's a steeper than normal learning curve relative to most of the games I play. Root is also enjoyable but it's more like multiple subgames running concurrently on the same board, which is fascinating. Unfortunately I'm not sure you can play it with just two.
Hogwarts Battle is fun and a good intro to deck-builders with how it slowly adds mechanics. I've heard good things about Marvel Champions and I think that's using mechanics similar to Arkham Horror LCG / LotR LCG and it's a great system.
Some other alternatives to consider coming from Hogwarts:
- Hero Realms - There's a co-op add-on for the base game and I think this would be a good next step if you enjoy co-op deckbuilders like Hogwarts. There's also an app version now which allows limited access to the game for free if you want to try the game without committing to it.
- Sentinels of the Multiverse - Non-deck-building game of a team of super heroes fighting a villain. Basically it's an RPG boss fight in card game form using original characters (that are clearly inspired by other things). Not sure how it compares to Marvel Champions though.
- Clank! - Deckbuilder with a board heist game but not co-operative. You're basically going into a dungeon to find a high value piece of loot and get back out before you get killed. Really fun game of trying to optimize your deck, while navigating the maze, while also trying to manage your risk of getting injured by creating noise and drawing the attention of the dungeon lord.