For general snobbishness:
* Super- (Super-snobbish)
* Ultra- (Ultra-snobbish)
* High- (High-snobbish)
* Over- (Over-snobbish)
For specific types of snobbishness:
* Social- (Social-snobbish)
* Cultural- (Cultural-snobbish)
* Intellectual- (Intellectual-snobbish)
* Elitist- (Elitist-snobbish)
Ultimately, the best prefix depends on the context and the specific shade of meaning you want to emphasize.