At least one reviewer had a Sony a6400 on hand while testing the new Fujifilm X-T30 and he decided to compare the pair pretty in depth. The Sony a6400 beat the Fujifilm X-T30 in AF hands down, but shockingly the reviewer calls it a tie.
Sony a6400:
24.2MP
Identical ISO performance up to 6400 ISO
Both Struggle to focus at 1600 ISO and beyond
Sony had an AF advantage because the model can go in and out of the frame without losing lock
Sony has digital stability via steady shot when filming
Bad rolling shutter during video
Sony’s colors are all over the place and need some tweaking
Sony’s skin tones are a bit flat and lacking detail
One handed shooting ergonomics
a6400 has bad controls but feels secure in your hand
Centered tripod mount that doesn’t block the battery
Forward facing LCD screen that flips up, which can be obscured
Not great for vlogging
No record time max so record until your battery dies or SD card fills
The overheating issue seems to be fixed
No audio out
Inferior video to Fujifilm X-T30
Fujifilm X-T30:
26.1MP
Identical ISO performance up to 6400 ISO
Both Struggle to focus at 1600 ISO and beyond
Fujifilm X-T30 forgets its AF subject if it leaves the frame
Fujifilm just has OIS while filming
No rolling shutter when recording video
Fujifilm has better color and gradients
Great skin tons with lots of detail
No real grip for one-handed shooting
X-T30 has better physical controls but doesn’t feel secure in your hand
Bad location of the tripod mount
No forward facing LCD
vlogging might be hard without a forward facing screen
Exchanged the h.265 encoding from the X-T3 and reduced the top compression level to 200mps h.264 and reduced the recording time for 4k to 10 minutes and 15 minutes for 1080p.
Can get 4:2:2 unlimited recording time to an external recorder
Audio out USB-C so USB-C headphones or dongle
Audio in is 2.5 and there is an adapter to go from 2.5 to 3.5
Superior video quality to the a6400
The better menu system, but comes down to preference
Both are an incredible value and you really should try them out in person if you can with a test SD card in a store.