As someone who plays both but prefers 4,I think they are equally good apart from the lacking traits and personalities in 4. They need to be played differently and 4 requires more imagination,direct control and story telling of your own. That's something I really enjoy. Obviously 4 is missing a lot of stuff. But to be fair it's not over. I do think that before it ends we will get updated babies,strollers,more kids stuff, cars, horses etc etc.
Somethings I don't believe will ever return to 4 like direct control of pets,open world,color wheel and stuff which is a shame.
One of the best things I love about 4 is how easy it is to mod and add cc to your hearts content. I have a lot of problems with 3 and cc tends to corrupt itself very easily for no reason. As a cc addict that's very frustrating for me.