For me though the prettiest of WW1 is the DH2, it looks so aggressive with the gun sticking out of the rounded nose and the lattice work behind
I can't really reconcile aggressive with pretty, and I find the Siemens-Schuckert to have a look all of its own. The cowling, spinner and four bladed prop wouldn't look out of place on a much later aircraft, but it's still a tidy, tight, well balanced little biplane without the sad, droopy looking nose of the Albatri - rather like a beautiful woman who's had one disappointment too many. The SS is a confident, good looking girl who knows she's going to be popular.
Of course, it's all subjective b/s.