Hmm, I started with all the NRaas bug fix mods, but in the end, I noticed that I had to use nearly all of them to make the game work as I wanted it to. I don't use Vector or some of the Story Progression personality modules (they are nice but get a bit much with a full town), but pretty much all the rest is now the core that holds my game together.
Other than that, there are the toddler mods that make life much easier: Arsil's Napping mats and the two by TheSweetToddler, Biggest Little Mod for Toddlers, and Children Can Carry Toddlers, which take some of the main annoyances with toddlers away.
I don't do laundry without Nonamena's Super Hamper anymore - otherwise the time laundry takes is not worth the positive effect, and I edit those into every single university household that has washing machines, or those come to a screeching hold.
Then there's Twoftmama's route fix, and No Route Fail Animation and No Foot Tapping by bluegenjutsu, which, together with a few system file edits (mostly concerning minimal distances sims need to pass each other), make routing much more smooth. Given routing is a major performance drain, this helps a lot.
The aforementioned Shimrod also has a few tuning mods that eliminate some of the more annoying wishes that constantly pop up, but that's already veering into mods that make the game more to your taste than mods you consider necessary.
