Comparing OGL rendering vs Metal by IDEA Editor Rendering Benchmark demonstrated that OGL looks better than Metal in almost 2 times
Measurements were performed for the build 2020/08/31 on MacBookPro mid2015 equipped with AMD Radeon R9 M370X 2 GB, Intel Iris Pro 1536 MB Graphics and two monitors (internal and external).

1) internal monitor (1638х952)

- OGL
avg: 116.1 FPS
median: 116.3 FPS

- Metal
avg: 53.6 FPS
median: 54.2 FPS

2) external monitor (2518х1342)

- OGL
avg: 52.2 FPS
median: 52.1 FPS

- Metal
avg: 33.8 FPS
median: 34.1 FPS

The above scores were produced based on 10-12 launches of the benchmark for each case monitor+framework.