In the field units of the German aviation of that era, the principle of the diversity of the machines adopted was dominant. Of the linear machines at the beginning of the war, of course, Albatrosses of all early types, as well as Rumplers, Aviatiks, LVG and DFW. In the summer of 1917 - Albatrosses from C.III to C.X, Rumplers mainly C.Ia, and DFW C.V. Roland C.II "Whales" were sometimes met in Galicia and the Baltic in the form of single specimens. Of the fighters, first are the Pfalz eindekkers, and of course the Fokkers. The Fokker E was the most massive fighter of the German Army on the Eastern Front. The first armed eindekkers by Fokker E.II - they began to operate in the winter of 1915-16. Of the D-type biplanes - Halbershtats, Fokkers and Rolands (there were most of them), from the end of the summer of 1917 they were gradually superseded by the Albatros D.III of the OAW production.
The German Aces on the Eastern Front at the time of the "peak" of their victories flew on the following planes: Hans Pipparth - a Roland D. II, K. Gallwitz - a Roland D. III, G. Knappe - the Albatross D. II. Only Pippart (who fought from February 1916 to April 1917) and Leopold Anslinger became the Ases on the Eastern Front.
Wilhelm Frickert on the Eastern Front scored 7 victories, but only 2 of them fell on airplanes (“Voisin” type), and the remaining 5 accounted for balloons. Karl Gallwitz "earned" in the East Iron Crosses of the 1st and 2nd classes, but both for 2 Russian balloons. https://warspot.ru/7408-tsveta-voennogo-neba-asy-dvuh-kayzerov-na-vostochnom-fronte