-Into the Future: ITF is broken... because their design philosophy is they didn't want to punish casual players for being casual... so instead of making everything from the future sort of difficult to obtain (honestly the "future tech" skill actually was an interesting concept and way to balance it) if you wanted to transport it into the past... they made everything available from the start.
It doesn't help that the Into the Future content is amazing... I won't lie, Into the future might be broken, and honestly the game BROKE my game permanently so I cannot even play The Sims 3 anymore, but they clearly tried harder on it then most of their expansions. The content in it is rather solid and the Supernatural Sim The Simbot is actually excellently designed and is to date the ONLY Non-human-based supernatural Sim who is customizable and gets their own clothes.
-Supernatural do NOT get it if you don't ABSOLUTELY want it in your game... because you might be thinking to yourself "Ohh, a few supernatural creatures around town what is the harm?" but no... Supernatural starts a supernatural INVASION! As well Zombies, which are super annoying AND overly frequent, cannot even be turned off unlike the other supernatural creatures. If you don't want the majority of Sims in your town being vampires, fairies, witches, and werewolves do not get this!
--Essentially Supernatural is the only expansion that can make your game, essentially, worse for having it.
-Pets... Actually is a lot more innocuous then its The Sims 2 counterpart where you heard baring and mewing ALL THE FREEKEN TIME! and wandering pets were an extreme nuisance. If you don't care about pets at all, then this won't interest you too much.
-Late Night I should warn is pretty much a "If you want to live in the city world" pretty much only and most of its content isn't integrated into the game very well. The VAST majority of its content is only accessible from the city. If you could care less about living in a city, don't get this expansion. Otherwise it is a very solid expansion.
-Generations: Honestly... this is actually rather skip-able... It wasn't unusual for long time players not to even notice this new content. It is probably the most lack luster of the expansion packs... and features one of the worst supernatural sims in the game (if the Mummy wasn't already the king it could compete) when playable. The Imaginary Friend is actually quite good as a NPC though.
-Ambitions: Here is the thing about Ambitions... The jobs the expansion adds, the ones you play yourself, get really tedious after a while and you will often just have your sims quit because you can't take it anymore. That makes the expansion sound pretty bad right? I mean its main draw was these professions like Firefighter where you actually fight fires!... Well in testament to this expansion, even if you eliminated that aspect from Ambitions it is still one of the best expansions for The Sims 3. It adds so many activities for you to practice, incredibly useful objects, and methods to change appearances and houses across town little by little... Its ONLY weakness is that Robotsims are pretty bad.
-World Adventures: Essentially a puzzle pack for The Sims 3... do not be fooled this is NOT a vacation expansion, and you are certainly not a sight seer in this expansion. It is one of the weaker expansions, but honestly it has its appeal. Just know what you are getting into. Outside Vacations, however, the game doesn't add too much to the game.
Ok I mentioned it a few times... but here is my rundown on what are IMO the three worst Supernatural Sims in The Sims 3 and why... Note I am excluding Zombie because... the zombie IS a bad life-state but the game doesn't disguise that fact. You aren't working for hours trying to get a zombie without knowing it is a disadvantage. In fact you can get temporary zombies earlier, so if you get a permanent zombie before you know you want one... its your own fault.
1) The Mummy: So you need the glitched Canopic Jars that can take a while to find as well as a SPECIFIC Sarcophagus that requires you assemble it from multiple pieces. This will take you a few hours... What does this give you? A Sim who moves REALLY SLOW!!! Cannot have their costume changed... and who offers no real gameplay changes other then a walking speed so slow, they cannot reasonable hold down jobs (leaving you to almost literally having them paint in one spot forever), take solace that they have very few needs to pester you with. The only reason to have a mummy is because... Its a mummy! that is cool!
2) Imaginary Friend: As a NPC this is actually one of the best supernatural sims as it actually changes up the gameplay quite a bit in interesting ways both mechanically and narratively... Playable however... The Imaginary Friend has two forms Sim form and Doll form. In Doll Form the sim commits the WORST sin any supernatural sim can have... He walks WAY TOO SLOW... and Human form is mostly normal other then having oddly colored hair. Other then Doll Form, something you will never use because slow sims are not fun, there are no gameplay changes for Imaginary friends other then renamed moodlets. Ohh also the Doll Form cannot be meaningfully customized.
3) Unicorn: I thought of putting the Robotsim in the slot for being slow and looking absolutely ugly as sin... but no I am giving it to the Unicorn. It could get on this list for being a Supernatural Pet for a game that had no Supernatural Sim... It could get on the list for essentially being a Horse with a horn, a glow effect, and essentially two powers that only give a minor buff or debuff... But what it REALLY gets on the list for being a "Cheat Supernatural" who comes with all its skills mastered from the get go making it actually a pretty boring Supernatural to get, and for its requirements to actually be somewhat annoying.