Don't forget Stuart's SPAD VII and Pfalz D.III, plus his wonderful Cauldron G.3.
Crashwoody has his SimTech SPAD XIII here at SOH.
Frank Elton has a wonderful Sopwith Triplane and a Fokker Dr.I also at AvSim and FlightSim. he also has a very nice Fokker E.V/D.VIII. If you want the best Fokker E.V/D.VIII, get the Baron's cheap payware (works in FSX also) D.XIII.
Benoit Dubé has the absolute best Nieuport 17, aided by SOH staffer Huub Vink. I think it is available here at SOH.
There is a fine Nieuport 11 at FlightSim, nieupt11.zip.
Milan Lisner's Brandenburg seaplane is not to be overlooked, Brandenburg_C1.zip.
Also Craig Richardson's Lorner seaplane at his Classic Wings website. Ditto his DH-2 and Sopwith Tabloid.
http://www.classicwings.net/
A. F. Scrub's Pfalz D.XII and Sopwith Salamander.
Stephen O'Leary's wonderful Sopwith Pup.
Stiz's AVRO 504, here at SOH.
Besides the others listed and what you have, that should do.
Oh no, how could I leave out Bill Lyons' excellent Graf Zeppelin, available at the Golden Wings website.
Caz