It all boils down to one question: which is more important to you: the experience of photography or the certainty of getting the shot?
Sony 6400 vs Fuji X-T30 Hands-on Mirrorless Camera Comparison - The Slanted Lens
Sony a6400 hands-on review: Sony ditches record limit and extends battery life - Videomaker
Sony a6400 Review
Fujifilm X-T30 II Review
Which is best for you: the Fujifilm X-T200 or X-T30?: Digital Photography Review
Fuji XT30 vs Sony A6400 Epic Shootout Comparison - Which camera to buy
Fujifilm XT30 review
Sony a6400: Perhaps the Best Camera Under $1,000
Fujifilm X-T30 II VS Sony a6400 Camera Comparison
Fujifilm X-T30 Review, A Pro Camera Priced Like a Phone