Spit XVI, While not the fastest its imo more dangerous that for ex a K-4. Even a Brewster can be dangerous if it has the alt advantage but a spit 16 can fight its way out even if it starts in a disadvantageous position. And even an average player can succeed in a 16 without hovering 5k above the rest.
It can also take enough ord to be a good tank buster so it can ruin the day for the tanker boys too.