There's the whole "the Saturn V needed to be 266 times bigger" argument, based on Von Buran's own design. Well, while reading astronautix, I happened to come across the page for his design. Turns out there's 3 reasons it so much bigger.
1. Used direct ascent, the most inefficient mission profile possible.
2. Used rocket breaking into earth orbit on return - Apollo skipped that step.
3. Was designed in 1952, a decade before the Saturn V, using early 50's technology and propellants with two thirds the performance.
4. The big reason: The mission would use three rockets for the exploration. Two of them would land a full 25 crew for 6 weeks. The third would land 10 crew and 259! tons of cargo. Total mass of the lander before landing on the moon would be 1109! tons.
So in short, if you use the most inefficient possible profile and early 50's technology, and send a lander that weights over 1100 tons instead of 15, and try to land 32 times as much on the lunar surface, then, well, actually Von Buran never actually designed a rocket 266 times bigger. It would be assembled in orbit via 360! shuttle flights, each carrying 33 tons. So the claims falls flat on its face even then.
Useful counterargument, anyway.