Enigmatica6 VS UsefulMods

The first modpack I ever played was enigmatica 6 expert. But i think plain enigmatica 6 would be better for your first time! https://www.curseforge.com/minecraft/modpacks/enigmatica6

There are tons of modpacks for 1.16.5 and up. You should try out Modpack Index if you have some mods you know you want and don't know which packs have them (I recommend sorting by number of downloads to help filter out the chaff). You didn't really give any rules so how about FTB Endeavour as a decent choice for a general kitchen sink pack on 1.16. You could also try FTB One if you want something really new, AKA 1.19. Enigmatica 6 is another high-quality 1.16 kitchen sink you could check out.

The one thing that I absolutely take issue with is that Enigmatica packs are objectively high effort and have been polished and improved over a huge amount of time - you can go look at the GitHub pages for each of them and see just how many commits there are and when they were made. For E2E, there are nearly 1k commits over five years - (https://github.com/EnigmaticaModpacks/Enigmatica2Expert/commits/master) - that's far more than most packs. Enigmatica 6 has over 10,000 commits (https://github.com/EnigmaticaModpacks/Enigmatica6/commits/master), which is the most I've seen in any modpack so far (and here I was proud of my ~1.3k in Valhelsia 3).

E6 IP & link - 91.208.92.218 https://www.curseforge.com/minecraft/modpacks/enigmatica6

Enigmatica comes in two flavors (four if you count 1.12.2 and 1.16.5). Did you play the regular version of Enigmatica, or the Expert version?

If you want a really good kitchen-sink, you gotta jump into Enigmatica 6. It's unbelievably well made and works super well. You can check it out here.

Perhaps try Enigmatica 6 or All the Mods 6

Perhaps FTB University or FTB Academy may be good as a first introduction to modded. For something slightly less aimed at walking beginners through, I would recommend Cuboid Outpost or Enigmatica 6. For a difficult pack, Multiblock madness could also fit quite well

Perhaps try All the Mods 6 or Enigmatica 6

There's tons of mods that do what Optifine did now. https://github.com/TheUsefulLists/UsefulMods

You can try Java tweaks - https://github.com/brucethemoose/Minecraft-Performance-Flags-Benchmarks or performance mods - https://github.com/TheUsefulLists/UsefulMods

Reference this list of performance mods, find your version, and ensure you're using as many as possible (as long as 2 don't conflict.)

Just an FYI, that list has been archived and is no longer being maintained. Use this instead: https://github.com/TheUsefulLists/UsefulMods