Buy the X-M5 if you are making video.Up to 6.2K capture against 4K30 is not a specification you need in order to publish 4K — it is a specification that gives you room: oversampled detail, the option to crop or reframe a 4K timeline without losing resolution, and headroom for stabilizing a shaky clip in editing. Add Fujifilm’s film simulations, which are genuinely useful if you would rather not grade every clip, and the X-M5 does more of what a video creator actually needs.
Buy the a6400 if you are taking photographs.The reason is the viewfinder, and it is a bigger deal than the spec sheet makes it look. A viewfinder lets you see your frame in bright sunshine, where both of these cameras’ rear screens become mirrors; it steadies the camera against your face, which buys you a stop or so of handholding; and it keeps you composing rather than chimping. For stills the X-M5 asks you to hold a camera at arm’s length and look at a screen, which is a phone workflow with a bigger sensor attached.
Buy the a6400 if your camera will get rained on. It is sealed against dust and moisture; Fujifilm does not publish sealing for the X-M5, and you should treat an unpublished figure as an absence rather than a maybe. For hiking, travel in bad weather, beaches and anything dusty, that is a real difference in what you can comfortably do.
Neither one has in-body stabilization
This is the specification people assume a modern camera has, and the one most likely to disappoint here. The X-M5 has no mechanical stabilization at all and offers digital stabilization only in movie mode; the a6400 is in the same position. In practice that means handheld walking footage from either body looks like handheld walking footage, and low-light handheld stills need a steadier hand or a faster lens than a stabilized camera would.
There are three ways around it and all of them are cheaper than buying a stabilized body. Use a lens with optical stabilization, which both systems offer. Put the camera on something — see our travel tripod roundup. Or, for moving shots, use a gimbal, which does what in-body stabilization cannot: our camera gimbal roundup covers the options, and image stabilization explained sets out what each type of stabilization can and cannot fix.
The lens systems are the long-term decision
Bodies get replaced every few years; a lens collection lasts a decade. This is where the two mounts differ most.
Sony’s E-mount is the largest mirrorless lens system there is, with decades of first-party glass and the full Sigma and Tamron catalogues behind it, which means there is a cheap option, a sharp option and a fast option at almost every focal length. Fujifilm’s X-mount is smaller but thoughtfully built, with a strong lineup of compact primes that suit the cameras they are made for, and film-simulation color that is part of the system’s appeal rather than an afterthought.
The practical question is what you want to add first. If that is a fast prime for portraits or low light, both systems answer it well — see best prime lenses. If it is a specific specialist lens at a specific price, Sony is more likely to have three of them.
Where the money actually goes
Both bodies sit in the same part of the market, and both are frequently discounted, so check the live prices in the table above before you decide anything on cost. The more useful framing: with either camera, the difference between the kit zoom and one good prime lens will change your photographs more than the difference between these two bodies will. That argument is made in full in camera or lens: what to upgrade.
If neither is quite right, two near neighbors are worth a look. The Fujifilm X-S20 is the X-M5 with in-body stabilization, a viewfinder and a bigger battery for meaningfully more money, and the Sony a6700 is the a6400 with IBIS, 4K60 and newer autofocus. Both are the answer if the missing stabilization is the thing you keep catching on.