My rig is old, beat up, limping on it's last leg (in fact had to reload windows on it just today.) I run TS3 and all expansion packs just fine. It can occasionally get a teeeny bit laggy but usually that just means it's time to reboot my machine. I only played TS4 for a free trial but personally, to me, the open world of TS3 is everything and CAS is second to that. But, and I haven't read all 3 pages so if this has already been posted I apologize, do *NOT* play TS3 without the NRAAS performance mods - it is completely unplayable without them imo. The mods take the lazy coding and glitch laden game and fixes like 99.9% of them painlessly. And the people there are incredibly helpful. And they work with a LOT of the modder community to try to be as compatible as possible and there's a bunch of gameplay mods. And you can know that they're 100% trustworthy. No I do not get paid by them, they're just that good. :) Just to be clear it wasn't TS3 that crashed my system. It happens with or without it, my rig just doesn't like Win 10.
Now that that's been said, TS4 looked too cartoony to me. I don't understand the term "Pudding face" so much, but you can really get some beautiful sims without any mods at all if that's your thing. It just takes a bit of practice or 5 minutes and a youtube video. :) If game play is your thing, if you like content, I've been playing TS3 since it was released and there are still things I haven't done, there are still parts that I haven't explored. My household consists of a genie, a werewolve, a fairy, a mermaid and a witch yet you can still be a zombie, a vampire, a mummy, a ghost, a plant sim, an alien... I can go jet skiing, scuba diving, snow boarding, to China, to France, to Egypt, to the FUTURE! And that's not even a drop in the bucket of the ocean of stuff to do. I can drive a boat, a sports car, a motor cycle, a jet pack, a horse, a truck, a unicorn, a moped, a bike, my own two feet in a jog to work, my HOUSE. I can be a fireman in my whole town, I can literally see my kids go to school or play in the park across the street from their grandparents that live on the other side of town while I work at the hotel I own out in the middle of the nowhere while I drive my house around in the ocean, see it all happening at the same time and FEEL that connection. When you zoom into the spring festival downtown and you see your sim's parents whoopin' it up on the dance floor? So fun. When your kid asks if they can go to their friend's house after school and you can still play both? When you can have that open world? That's my happy place in all of the Sims franchises to me. Without that there's very little reason to even care about the other sims in your game to me. Someone else said it earlier, it's like they're props. But when you are in "map" mode and you can see everything whenever? You can see the little old lady that lives next to you whippin' across a lake on her jet ski? That gives me SO much content that I'm just even witnessing, not responsible for but get to enjoy. Plus CAS makes every place unique. You can have an entire world that you designed where every single wall is different and that's not an exaggeration at all. CAS does take a bit to load but I just multi task during that time. I read or email or work or whatever. I play a lot of armchair catch with my dog. I get that it's a downside, but after trying TS4, I just kept waiting for an expansion pack exciting enough to give up the open world. The fact that TS3 still has so much more content than TS4, to me doesn't bode well for TS4 in my future. But everyone is different. My niece plays TS4 and loves it. :)