One of my favorites

This is a classic mod I still enjoy very much to this day. It's still under active development, which I find great considering how there are many great classic mods that have been abandoned. However, there are still some features yet to be developed (such as the much anticipated final boss).
In terms of the gameplay, the dimension as a whole is really nice and the boss battles are very fun.
In terms of aesthetics, I love the original Minecraft aesthetic, so it's great that The Twilight Forest follows the same style. In addition to that, everything the mod adds looks beautiful.
In terms of performance and stability, I have only really played the mod in the 1.12.2 version for a long time (I plan to play the newer versions eventually), and it's not that good on its own, but the Phosphor mod can easily fix that in 1.12.