Supernatural has one of my favourite worlds, Moonlight Falls. It has lots of empty spaces for me to place my lots in so I like the world. It has some cool goth style furniture and objects if you are into that. Also has a lot of plants, and beekeeping if you want to enhance your gardening experience. There is also a gem cutter. Also has small interactions like skipping stone in the ocean, checking under the bed for monsters etc. These are all the stuff that I have in my mind that doesn't have occults in it. Also as far as I noticed the EP is not buggy at all.
Pets is literally pets as far as I know so if you are not into that I don't think this should be your first pick. I also don't use pet stuff and this pack only serves as a large stuff pack for me.
Isla Paradiso itself is a buggy world but you can install other custom worlds that has its features and enjoy the pack this way (That's what I did). I never managed to fix Isla Paradiso to a state where it is actually playable, no matter how much I tried. Even if nothing works out, again it can serve as a big stuff pack, and I really like the resort feature of the game which you can use in any world.
With Into the Future you can travel to the Future World. It is a nice looking world with nice looking lots so I enjoy staying there occasionally. You can change the future between 3 states (Distopian, Utopian, Normal) with each having some unique stuff to do. If you want modern looking objects in your game this EP is also cool with that. It has almost every object in a futuristic way. Like it has an easel that produces holographic paintings, holographic pets, holographic plants, sonic showers, holographic TV etc. Has some cool looking transport options like jetpacks, hoverboards, flying cars. You can have glass roofs (Not a full blown fleshed out feature, it is done with objects). You can place anything that requires it to be on a soil inside with soil rugs. These include plants, rocks, trees etc. Plumbots are easily the most fleshed out occult in the entire game, with their own traits and lots of customization options. That is what I remember about ITF from the top of my head. I like this pack because I like Sci-Fi stuff and I enjoy the gameplay and some occasional references to stuff like Back to the Future and Doctor Who. You said you didn't know that much about this pack so I went a little overboard with some details, hopefully this should be good enough.
Showtime I guess can also be fun with its new world, and some of the objects like karaoke machine, dominoes and other stuff? I honestly don't like this pack that much but it is fun if you are playing with its features for the first time. Also it has genies which I enjoy.
I would probably pick Supernatural because for me it is the most fleshed out pack in this list. Pets is also equally fleshed out but I just don't like Pets, and they can cause some routing issues in problematic worlds. If I were to pick I would first pick Supernatural, then Into the Future, then Island Paradise, then Pets, then Showtime.