Honestly, I felt the original Hyrule Warriors was better than Age of Calamity in every way. From a pure combat perspective, I feel they're equal in fun factor, but the original game has a much larger roster of playable characters, way more to do with the various Adventure Mode maps, tons of amazing weapons and costumes to collect, a pretty cool story with neat, original characters, and it doesn't run like complete ass like Age of Calamity does. Most of all, AoC is a very poor prequel to Breath of the Wild, and if I told you why, it'd be a big spoiler. But I'll say this: don't believe Nintendo when they claim that this is the tragic tale of the Great Calamity finally told.
The worst part about the game for me was how much it forces you to grind for items to upgrade your characters, weapons, and overworld facilities. Sure, the original HW had some grinding, as well, but you always felt like you were making some kind of progress by doing it, like getting to the next Adventure Mode unlockable. In AoC, you'll be playing the same maps over and over to try and get more Lizalfos tails or whatever. It really starts to drag in the end.
I'm a massive Zelda fan and buy every game in the series (I just slogged through Skyward Sword HD despite never really loving that one when it originally came out) and even I'm questioning how much I want AoC's expansion pass. If you're torn between the two HW games, I recommend the original to get the most content. Plus, it's just such a love letter to the Zelda franchise.
