-places nitor in the thread to lighten the mood-
For my personal Infinity client, I added Iguana Tinkers Tweaks and Storage Drawers. The random modifiers are a fun reward for putting in the work to level them. Plus, no half-hour portal to the nether, you have to work for it, and make a smeltery.
I'm a more magical/decorative mod enjoyer, as I do not have a long attention span for doing high tech mods. Get bored after a few weeks, and hop to another pack. Granted, I'm still living in a hill that I hollowed out and when I get a wand of equal trade, it will be made into a lovely wooden hobbit hole, after the lava pool in my basement is drained.
What I would like to add potentially for myself later
Morph
Bat mode for the win. No, I'm not addicted to flight... not at all. -hides wings-
Villager's Nose.
I've only found two villages in exploration, and that is a fun/villager humiliation mod to grow-your-own-villagers. I can't help wondering if any villagers in Villager's Nose will grow into werewolves...
Minecraft Comes Alive
Squidward villagers are boring. Adopt babies, and send them fishing. Never run out of fish again. Wish the adults could still do 'chores'.
Doggy Talents
I have not done hardly anything with this mod, but what apprentice witch can be without their own high powered superdog Bolt?
ExtraBiomesXL/Alternate Terrain Generation
Biomes o Plenty is so used, Its in practically every worldgen geared pack I've played recently. BORING. Granted, I dont' wish to start my world over, so next world.. Maybe.
Mob Drop Crops
You like dying a lot in the start and racing back for your stuff? No? Neither do I. Play peaceful and go get your own mob drop crops. That, and enable the ender lily seeds recipe.
Automagy
Because auto livingrock/smooth stone = YES with magical redstone. Block breakers are boring, but needed... which one does silk touch again?
Some mod that makes horses better
Someone please make a split-off of Mo-Creatures for solely the horses? Or something similar to Horsey Talents, where you can have a superhorse.
Tails
Dragon tail for the win.