How much are you into the way the GR works? In my experience, specs go only so far in order to describe how a camera feels in use - and gets used. The GR is quite unique and very satisfying: Small, capable, respsonsive, fluid in use and pleasantly customisable. And the IQ from this 16MP APS-C chip is astonishing - the lens plays a big part in this, of course.
Fuji make greast glass, so the lenses won't really be the problem. However, if you're into RAW capture (i.e. maximasing IQ on your own), I'd advise against the Fuji - it's still a bit cumbersome to get the most out of those files, though no way as bad as it was. But if you're into JPEGs, the Fuji will probably easily outperform the GR - its muted JPEGs aren't for everyone, though I find the OOC B&W images from the GR very nice. But: Why the X-Pro1? It's really dated by now, and I think you'll get a lot more immediate performance from the X-T1, X-T10 or X-E2 (the latter would only be a valid choice if the rangefinder thing is important): They have better processors and firmware and respond quite a bit quicker - with the X-E2 bringing up the rear. You will know by now that the GR simply feels very responsive - and I find it quite hard to change (back) to (much) slower cameras from there. For example, I had tried the Panasonic LX100 before buying it and liked the perceived responsiveness - but it feels positively sluggish in comparison with the GR; thankfully, the AF is a lot better, and the zoom and EVF make for a great shooting experience in its own right. But I couldn't let go of the GR as intended initially - it's just so much more fluid ...
As for the Sony cameras, I found A7R surprisingly unwieldy in use, slow and quite a bit clunky, and there are apparently serious issues (shutter shock - generally a cumbersome shutter mechanism). I haven't handled the A7RII yet, but the A7II, which was already a lot(!) better behaved in every respect, especially speed and sound profile. But here's the catch: Even the A7II isn't a fast camera to deploy in comparison with the GR; I hear the A7RII is better, but with that, you end up with huge files you have to know how to handle before you profit from them. And coming from something as effortless in use and post as the GR, you have to learn how to control your shots a lot better - or you end up with mushy files that mock the price you paid for the camera (shutter shock again, but general camera shake - at that kind of resolution, any kind shoddy technique will show most of the time!). The GR makes controlled shooting a breeze - and is also more forgiving. Of course, the A7 series surpass the GR in terms of image quality, and the R models have a crazy pixel count in their favour - but if you shoot them with legacy glass, you might not be able to use that anyway (as nice as they render in some cases, they're not made for that kind of resolution - heck, there was no way of intentionally doing that back in the day before CAD and micro-measurements). I'd consider that quite a mistake, all the more so because those Sony bodies depreciate extremely quickly (that's Sony's fault for pumping out new models all the time) - you will lose a lot of money if you dare to reconsider (which Sony try to force you into every year - at least).
All that said, I freely admit that my small system of choice is mFT - and specifically Olympus. Both Panasonic and Olympus make very interesting, innovative and capable bodies - and there's a lot of really good glass to be had for them, and often at bargain prices. And everything is nicely light and small (even the bigger lenses
). But admittedly, as good as they may be, they're certainly no match for the GR IQ-wise. Anyhow, I personally like the results from the still-current 16MP mFT sensors, the RAW files have potential and can be handled much the same as the GR's. Most models have EVFs - which I love enough to use those cameras more than the GR. If you don't intend to print large, you'll not miss out on a lot of possibly IQ - at screen sizes and prints up to 20x30'', the mFT cameras can keep up nicely (up to ISO 1600, that is). And I personally never print that big ...
All in all, I'd say you have to determine subjects and intentions first and look beyond the poster children ... So, if I was to go for manual focussing or legacy glass, I'd choose the A7II - price-wise, it's a fair offering, and you won't spend money on pixels (and technology) you have no intention and/or immediate occasion of using. It's quite a nice camera to use once it's switched on. And of course, there are the Olympus OM-D and Panasonic GX cameras ...
M.