I haven't really met many really nasty Corgis of either type, although I have known some who were reactive on lead to other dogs. Many won't tolerate being handled roughly either. Sort of typical herding dog stuff. I'm not sure it's fair to judge a breed based on how untrained pet ones behave in stressful settings.
Ziggy, our rescue Cardigan is crazy. Super high drive and intense. But pretty calm around the house. I sort of wish he was typical of Cardigans. Most I have been around seem to be pretty low drive and many show breeders have been selecting for exaggerated characteristics, which IMO makes them less athletic.
You can see Ziggy in my flyball class videos:
YouTube - Flyball Beginer Class YABTC