Nobody can really tell you which of these bikes will be faster from pictures, but you can look at some individual features and judge those. Really the VB doesn't make any disastrous mistakes. The fork crown and lower headtube are a bit odd. The head tube trailing edge is a bit narrow, so that might be a bit unstable at high yaw, the flat transition from top of bb to seat tube isn't the best, but with the mess that the airflow is in that area, it's probably irrelevant. The seat tube and post are a bit wide. The leading edge on the lower section of the fork is flat. The head tube is very narrow, so that's its biggest positive. Can't really say how fast it is when it's all put together.
The advantage big brands have is that they already have libraries of the optimised tube shapes and lots of time and money to spend on optimising every tiny detail (a real pain in the ass). Velobuild really can't afford to do that so they just throw deep tube shapes at the problem, but that's not really as good.
I'd lean towards the S5 simply because of the gap in resources and it tests well (though my suspicion is that the wind tunnel is more flattering to it than the real world), but I wouldn't expect the VB to be a parachute either.