What are the best "must have" mods?

I have never really used mods. I have a few little things, and I have used the traveler mod a few times. I don't know a lot about mods but now that it seems like there will be no more updates to worry about I was thinking about giving them a try.

I was looking through nraas earlier, but I was curious what you would suggest?

I like to change up the way I play. I do everything from legacies to changeing the race/color of the town through whoo hooing.

Really anything I get bored easy so I am always looking for some thing new.

Honestly it depends on the status of your computer and game.
But if you want to be SUPER cautious and have a good amount of control over your game, I would suggest:
Master Controller
Story Progression
Overwatch- helps keep track and fix of in game issues
Saver- Helps remind you to save often to prevent game corruption
Traveler- helps with the bugs related to World Adventure and adds flexibility with those worlds as well

These and many more are all provided by Nrass...he be awesome =^^=

I agree both with Carlos and Stabitha666 , also an other good mod is Register which is to purview  the manipulation of the service and role sims in your town. http://nraas.wikispaces.com/Register .

NRass mods are great. I have been using them all for years. Though Twallen retired. His work is being carried on, and yes, they are still tweaking things, even though game has reached its "end of life" in retail.  Also for UBER AWESOME vehicles? Nobody can touch freshprince he has a lot on MTS, but here is pretty much every car he ever made. Many in mod, and package form. Use S3PE to make his car mods into 1 large mod. (tell how to use s3pe one MTS, and the S3PE website. You can have them all, without added load time pretty much.  http://www.freshprincecreations.com/

Wow very Nice Confucious I never thought about doing this but I am now excited for having you bring such a great addon to the game. I myself use http://www.thesimsresource.com/ and I have added very much of the downloads they have and they themselves make sure it works with the latest and final download of the Sims 3 which of course is 1.67. You may want to check it out for anything that you might or may be missing. You may also want to use Ad-block for your browser so you do not have to sit through the ads.


http://www.thesimsresource.com/

Not going to lie, I've been modding my games since The Sims 1.  Mods are essentially a way of life for me, and it's the first thing I'm looking for when we release The Sims 4.

It depends on what type of mods you are asking about.  Are you looking for mods that improve the gameplay (essentially fix it), or that actually alter the game to fit your play-style a bit more?  Nrass mods, in my opinion, are more necessary than "fun".

I usually have at least 10+ mods running on my game all at the same time, however, that includes slider mods due to the fact that I hate how they made TS3 sims' faces appear.  Pudding faces!

I'd say the essentail The Sims 3 mods are Twallan's NRaas mods; Overwatch, Story Progression, Woohooer, Relativity, Careers and Master Controller to name a few. Awesomemod, teen pregnancy, retextures and remodels are also a must-have in my book.

I am using the whole Nraas collection of mods.

I love them all.

Very useful anyway,