Bristol F.2 The best 2 seater fighter of WW1. It first gained infamous reputation points when the first patrol was met my Manfred von richthoven's Flying circus, in wich 4 out of 6 planes were shot down.
However, it was then discovered, the F.2 was very manouverable for its size and weight, and became a very effective fighter. It could keep up with most 1917 german aircraft(and even 1918 ones) while having a strong 'sting in the tail" with either a single or dual Lewis gun.
It was also considered one of the sturdiest designs in the Royal flying corps.