I suggest City Living if you enjoy living with the challenge of a confined area until your sim becomes rich and buys the penthouse. It's hard to have big families in City Living, but if your sims move out of town the festivals are really fun to go to in my opinion. The flea market literally sells collectibles too if you like collecting in the game. The humor and hijinks festival is a party to behold, especially for my comedian sims. The Romance festival makes it easy for your sim to get married on the spot, which is good for drama lol. I haven't been to geek con lately, but I remember it being really fun for my gaming and nerd sims.
If you really love animals I suggest getting Cats and Dogs, but I'll warn you here. Beyond training your pets and owning a vet shop there's not a whole lot to do besides watch your pets. The emphasis in this pack was probably the create a pet tool, which is VERY in depth, and even has a color wheel and a paint brush to customize fur and stuff. Pets aren't controllable like in the sims 3, and you can't view their needs or send them to pet jobs like in previous games. It's very realistic, and I love having pets in my game, but the pack was lacking in interactivity with your pets. I'd appreciate just having pet jobs and being able to see my pets stats. That being said, it's still fun, and the veterinary business should you decide to play it is very interactive and kind of makes up for not having pet careers and stats.
I actually can't decide for you, because I love both packs so much. I'm a huge animal lover so it would be hard for me to say I would rather have skyscrapers than pets. And city living is fun too, so it's a close call for me. I can just give you my review of each one and hope you can make a more informed decision from it.
Edit: Grammar fixes.