This post contains multiple SlimeFun 4 addons that would be helpful to have added to the plugin list for players to use, as well as a reason why (Note: You can find the addons here ):
Slimefun 4 OFFICIAL Plugins:
ColoredEnderChests: Useful plugin, allowing you to have multiple ender chests.
HotBarPets: This plugin allows you to have hotbar pets. On one server I play on, it would be a great addon to keep players coming.
SoulJars: Allows you to craft slimefun spawners from killing mobs with a soul jar. Keep in mind you craft this so it is NOT the same as MobCoins
ElectricSpawners: Allows you to run spawners off of the slimefun electricity. This adds more use to electricity other than running certain machines.
PrivateStorage: Allows you to craft a bunch of different chests, including private chests, explosive resistant chests, and chests corresponding to every wood type.
ChestTerminal: Allows you to make a massive chest array where you can store and search for items, making it useful for managing a storage system.
Barrels: Allow you to store MASSIVE amounts of a specific block, but nothing else. Useful for farms.
ExtraGear: Allows you to craft weapons and armour from the alloys made in slimefun. This gives more use besides machines and items.
ExtraHeads: Allows you to decorate your house with more head drops from mobs.
SlimeFunOreChunks: Allows you to mine slimefun ore chunks from the GEO-Miner (slimefun Item). This is useful because it makes it easier to get certain ores and it can be automated easier.
DyedBackPacks: Simple addon that lets you dye the backpacks found in slimefun. Helps with Organization
3rd party addons (Also on TheBusyBiscut's github)
SlimeXpansion: Adds over 30 items to slimefun, giving you more items to work towards and use
I know it's a bit of a list, but you don't need to add all of these. I personally reccomend ChestTerminal, ExtraGear, and SlimeXpansion as those are the best in my eyes. Remember, you can get them all here