no doubt the Patek has far more modifications made to it then the Vacheron Constantin. From a pure finishing standpoint I would suspect they are pretty close; and the VC could easily pass muster for a Geneva Seal if VC so chose. Choosing between them really comes down to what you are looking for.
Being a bit more traditional I find a classic size chrono movement like this belongs in a classic sized case. I feel PP is a bit over the top in using its large case for this movement. Yes, PP did make a few vintage chronos in this large case size but the vast majority of PP vintage chronos were in traditional sized cases of 36-37mm diameter, which were considered quite large in the 40's and 50's. This is where the VC really shines.
Cost would also enter into the equation. The Patek is expensive for a chrono only watch at about $30k; the VC, by contrast, is $17k. Put side by side ..... looking at all aspects such as size, design, and finishing, I found that the VC is a screaming bargain at its price point. I don't see the overall value of the extra $13k for the Patek Philippe. But for others, they could easily justify the difference in cost. There is no wrong or right answer here.
I've had my VC Chrono Historiques since early February and it has already moved up to '10' status on the Evitzee scale of permanence which is shared by only four other watches in my collection.
I find this watch has one of the prettiest dials of any contemporary watch and eminently wearable. It looks old and new at the same time.
Patek Philippe, Vacheron Constantin or maybe the other great handwind chrono, the Lange Datograph, there just aren't a lot of top grade manual wound chronos being made anymore.