Gotta disagree with the people hating on Eternal here. Eternal is very different than 2016, so it's understandable 2016 will be some people's favourite.

The key difference is that Eternal has a much stricter way the game wants you to play it. When speaking about the changes, the devs pointed to some incredibly lame review footage where a game journo beat several levels while barely turning the camera, ramming around corners and only using the shotgun. You can play 2016 that way, simply forcing a gun you like as a silver bullet into every scenario.

Eternal will demand significantly more from you. Guns to target weak points, special interactions like grenades for cacodemons, enemies like marauders who want to dance at specific ranges or require trickery like shooting rockets at the ground behind them to beat them, you'll even need to cycle between multiple guns to skip lengthy reloads to get your full DPS. You need to make macro level decisions constantly, not just point at the nearest demon and shoot it. It's often referred to as "combat chess". If you give yourself over to it and play with an open mind, getting good at Eternal's combat is fun as hell, and is likely the best combat I've ever experienced. You feel like a beast when you're successfully executing the dance, 2016 will feel like a slow slog in comparison.

Bonus review, since I'm here. TDA is a total shakeup again. Combat is slower and more flexible, striking a middle ground between 2016 and Eternal. Many of the varied tools you needed to swap weapons for in Eternal are just shield abilities you always have here, so you can pick a favourite weapon and stick with it again. Should, actually, swapping around is slow and guns don't have huge speciality advantages. The game leans more into being a power fantasy, but the shield is very good, you don't have to earn it nearly as hard as you did in Eternal. For reference, I fairly easily beat TDA on Nightmare for my first playthrough, and failed to do so when returning to Eternal that same year, getting totally walled in a fairly early level. They did rebalance the campaign since I played TDA though, and it's supposed to be harder. Planning to check it out in a replay before playing this DLC.

All in all, I really love that each entry is bold enough to totally revisit the core design and do something fresh. Eternal is basically the perfect version of that vision, especially in the DLC. I might have loved more of that, but it there really wouldn't have been anything new to add. So TDA does its own thing and does it really well. Each entry is radically different, and they're all awesome (although I really can't go back to 2016 lol).