Youtuber Jared Polin has posted the full review of Eye AF comparison on Sony a7R IV (B&H/Amazon/Adorama) and Canon EOS R5 and Nikon Z7. From the result, we can see that Sony a7R IV has very similar eye AF performance as Canon EOS R5. You can take a look at full review above.
Comparison
Sony a9 II Vs. a9 SD Cards Write Speed Comparison
Here is a comparison video about SD cards write speed tests on Sony a9 II and a9. From the result, we can see that Sony a9 II is much faster than a9 in 5 second burst:
Specs Comparison: Sony a6400 Vs. Nikon Z50 Vs. Canon 6D Mark II Vs. Fujifilm X-T30
Nikon has just announced the new Z 50 APS-C mirrorless camera. Here is a quick comparison of Sony a6400 Vs. Nikon Z50 Vs. Canon EOS M6 Mark II Vs. Fujifilm X-T30.
Dynamic Range Comparison: Sony a7R IV Vs. a7R III Vs. Fujifilm GFX 100
Photons to Photos has tested the new announced Sony a7R IV (B&H Photo Video/Adorama/Amazon) full frame mirrorless camera. Here is the dynamic range result for Sony a7R IV above.
Specs & Size Comparison: Sony a6600 Vs. Canon EOS M6 Mark II Vs. Fujifilm X-T3

Here is a specs and size comparison of new announced Sony a6600 (B&H Photo Video/Adorama/Amazon) with Canon EOS M6 Mark II and Fujifilm X-T3 mirrorless cameras. You can take a look at below:
Specs Comparison: Sony a6100 Vs. a6400 Vs. a6600
Reivews: Sigma 35mm f/1.2 DG DN Art Vs. Sigma 35mm f/1.4 DG HSM Art Lenses
Here are some comparison reviews of new released Sigma 35mm f/1.2 DG DN Art lens (B&H Photo Video/Adorama) with old Sigma 35mm f/1.4 DG HSM Art lens. The new Sigma 35mm f/1.2 DG DN Art lens is twice expensive than Sigma 35mm f/1.4 DG HSM Art lens. So how is the image quality ? You can take a look at some comparison reviews below:
Specs Comparison: Sony a7R IV Vs. a7R III Vs. Nikon Z7 Vs. Panasonic S1R

The Sony a7R IV is the latest full frame mirrorless camera from Sony, it has a ground breaking 61MP full frame sensor. Here is a quick specs comparison for Sony a7R IV with a7R III with Nikon Z7 with Panasonic Lumix S1R. You can take a look at full specs comparison here.