While the dog undoubtedly has more emotional impact, I actually prefer the version with the ox.
In my head it helps explain why the host uncharacteristically dies
before the Alien births, because ox ribs must be pretty tough compared to human (or dog) ribs, right? So maybe it couldn't get out at the usual stage, kept growing, and eventually the ox dies from asphyxiation when this thing fills up too much its chest cavity. Then when it's big and strong enough, it busts out. The late birth is explained, as is the fact the "bambiburster" itself is so much more developed than normal when it finally emerges.
Also Gregor's like about queens and whores in the added slaughterhouse scene cracks me up, so I wouldn't wanna lost that

Tbh the only thing I don't like about the extended version is the music getting ruined during Ripely's death, but in terms of her chestubrster I'm with Fincher - the scene's so much better without it.