About a year or so I go I began researching my first "real" camera, and came to the same dilemma - a6700 or R7. My primary needs were different though, with action telephoto being my primary focus (airshows and wildlife). I research for many months, both the cameras and about a bazillion lenses (mostly for Sony, obviously, as there weren't many Canon lenses to research). I went for the a6700 for a number of reasons.
Size was a primary reason, and as the smaller camera, the a6700 was the obvious winner for me. Not just the size of the camera, but the size of the lenses I had to choose from.
Autofocus was another category where the a6700 won. I never saw anything bad about the R7, but everything I saw about the a6700, other cameras with the same Bionz XR processor, and just Sony in general, I knew I'd have a better time with the a6700. And I can tell you that the AF on it is absolutely ridiculous - I've only used it on aircraft and animals, and while it doesn't do great with lizards, it's amazing with birds and mammals. With aircraft it actually tries to center focus on the cockpit as though it's the "eye" of the plane, just like it does with animals and humans (and if it's not the cockpit it's the whole aircraft).
Speed was a concern, and although the R7 has faster framerates, it suffers with its shutter modes in a way that wasn't acceptable for me. Electronic shutter suffers from a slow readout speed, causing slants with panning and typical wobble/bending/fragmenting that you see with rolling shutter. No big deal for me since I expected to shoot mechanical shutter. However I saw lots of reports of shutter shock with the mechanical shutter, where the force of the shutter causes internal vibration that shakes the sensor. If you're shooting stills, the electronic shutter should suffice for you. The faster 15fps of the mechanical shutter vs the 11fps on the a6700 may or may not improve the "keeper" rate, but it was my instinct that even with the slower a6700 I'd have more keepers because of the better AF and less worry of shutter shock.
The biggest concern was the available lenses. In my case, with long telephoto zooms, the Sony was the obvious and really the only choice (for my size/weight preferences as well as my budget). However it was the availability of the other lenses that really sealed the deal for me. Now, at that time, when I finally made my purchase (in November), only the Sigma f1.4 prime trio was available. I needed a good wide angle zoom, and the Sigma f2.8 10-18mm was not available for Canon. Nor was any superzoom, which I was considering (and still have not purchased), nor was there a good "standard" zoom. Now those lenses are available, including the Sigma 18-50mm f2.8 "standard" zoom (I wish the Tamron 17-70mm was though).
Even with the additional 3rd party APS-C lenses available for RF mount, the selection is what I'd consider barely adequate for general use; you're still stuck with what's available with no other option than that small handful, and while they're good, they might not be the lens you wished you had. It's also lacking in some specific lenses that are available for other mounts, but not for Canon RF.
As for adapting, I'd only bother adapting Canon's own EF mount lenses and wouldn't expect frustration-free results with 3rd party lenses or lenses meant for other brands.
I will point out that Canon is working on the R7 Mark II. Could be soon, might be closer to the end of the year. Word is that it'll be more "premium" (and thus more expensive), and that it'll fix the shutter issues with the R7. Everyone in the rumor biz thinks it'll at least get a stacked sensor for faster framerates and less rolling shutter. Some think that it'll even do without the mechanical shutter, which if true means that the electronic shutter and readout speeds will be good enough that the mechanical shutter is indeed unnecessary. Of course, it'll still suffer with the limited lens selection. To me it seems like the Mk II will be catering more towards the wildlife/action shooters that like using a crop sensor body with supertelephoto lenses for the extra "reach" without the issues of using a teleconverter. Plenty of Canon R6 and R5 users also have the R7 for exactly that reason and are eagerly awaiting the MkII. While that doesn't appear to be what you'd be using the camera for, an upgraded camera is either good for you because it's better, or it's good for you because the older model will be cheaper.
I'm actually very eagerly awaiting the R7 Mk II, which I very well might purchase, depending on its actual specs, and subsequent reviews. However that'd be very specifically for aircraft/wildlife shooting, and with the 100-500mm (unless the Tamron 50-400mm miraculously is released for RF). I'd most likely keep my a6700 too for other use (because of its size, other lenses, etc).
As for other options, is there a reason you've ruled out Fuji? Granted, Fuji's autofocus is known to be not as good as other brands. If you're not shooting fast action though it should be adequate, and the lens selection is excellent. Lots of 3rd party options (although not as much as Sony), and their own lenses are great too. Check out the X-T50.
And finally, have you ruled out full frame as an option? You could pick up an older A7 III for about the same price, and while FF lenses are generally larger and more expensive that APS-C, for E-mount there's no shortage of 3rd party lenses that are way less expensive than Sony's...or Canon's or Nikon's. While you can still get that shallow depth of field with a large aperture APS-C lens, full frame will always be king in that regard (we'll ignore medium format for purposes of this discussion). I'm guessing you've already dismissed Nikon as an option - the Z50 II probably won't be adequate for you. The Z6 III is an amazing camera for its cost, and puts other "budget" full frame cameras to shame, but it's more expensive than the R7 and a6700, and then there's the cost of the lenses. A used Canon R6 or R5 (older versions) can be had for a good price too, but again there's the cost of the lenses.
All that said, the a6700 is probably the way to go, if only for the lens selection. It's not without its disadvantages. One of which is also an advantage, being its small size. However, that means there's not much grip to hold on to - your pinky finger will be dangling. This can easily be augmented with one of the Smallrig baseplates. The other most obvious disadvantage is the viewfinder. It's smallish and off to the side. I'd say it's adequately sized, but bigger would be better. The positioning may or may not be an issue for you. It kinda bugs me because it's not centered, which makes finding the subject and tracking it less instinctual, but that only really matters for fast action.
I love my a6700, and have zero regrets or doubts that I made the right decision. My only "regrets" are that the "perfect" camera/lens combo for doesn't exist yet. I wish Sony made an APS-C camera that was more like the R7, and/or that Canon had a mid-level supertelephto that was place between the cheap RF 100-400mm and the very expensive RF 100-500mm. But that's my problem, not yours.
