deGrom has more WAR by a fair bit, fewer walks, lower ERA by a lot, lower FIP, lower xFIP.
Sherzer has more strikeouts (260 vs 230) and a way better W-L record (16-6 vs 8-8) since the Nationals have scored over 5 runs per start when he pitches (vs Mets who score 3.6 when deGrom does)