I totally understand your choice to move over, I was in the same situation but decided to stay and update my gear to the RF system and wait patiently for the trinity zooms. Currently IMO the RF mount is only missing one important prime, the 24 or 35L. The 50 and 85 are already available.I have to say I am both jealous and sad about the Canon situation. I almost bought an EOS R from my 5D Mark III. Instead after reading reviews I sold off my Canon equipment and bought a A7RIII, 24mm GM F1.4, 55mm F1.8, 85mm F1.8, 24-105 F4 and 90mm macro.
I didn't expect it but I was utterly shocked at the resolution difference between the A7RIII and the 5DIII. Obviously the resolution is completely different but I think the AA filter not being present makes the biggest difference.
Comparing these new lenses to what Sony is offering it is incredible what the RF mount can offer...it was just too little too late for me. I wanted a F1.4 24mm or 35mm. I wanted decently sized (and priced) primes as well.
How long would it take me to get equivalent lenses to what I have available right now with the Sony system? Probably years. You can say just use EF lenses but that introduces complexity in lens swaps and removes a lot of size advantage.
I hope Canon does well with this mount...who knows maybe someday they will offer a really compelling package...all I know is right now I'm loving the Sony more than my 5DIII.
I had the 5D Mark III along with the 24-70L 2.8 Mark II, 35L 1.4 Mark I, 135L 2, and 85 1.8. I mainly used the 24-70L and 35L so selling off my gear wasn’t a huge deal knowing the RF zooms were on their way, and I prefer the 50mm prime over the 35 so that was a huge win for me. I did try the EOS adapter for using EF glass on the RF mount and while it worked beautifully, I didn’t like the extra length it added to my lenses. I prefer native glass on the RF mount, it’s so nice.
I am patiently waiting for the three trinity IS zooms for my new EOS R. Currently I have the RF 50 1.2 L and it is by far the best piece of glass I’ve ever used. I mean seriously, it’s that good and makes me excited to get any future RF L lenses. And the RF 24-105L with the nano usm is ridiculous for an all around general zoom, I honestly feel it’s probably as good as the current EF 24-70 f2.8 in certain situations due to the 5 stop IS.
Right now, that simple kit suffices for me while I wait for the new zooms which should be out in a few months.
So in regard to your comment about waiting years to get that setup, IMO it’s almost here besides the 24 or 35 prime. The RF glass is pricey, but I can say it’s fully worth it and that’s even with a medium level EOS R body. Imagine when the pro version is released and can be used with this amazing RF glass, there will be a clear difference in brands I believe and it will be due to the RF glass.
Canon knows a 24 or 35L (or both) is needed when they have their pro body out, it won’t be long considering 2020 Olympics are coming on their home turf. I imagine their lineup by then will be insanely good and certainly have all needed zooms and main primes.
Sony obviously has the better bodies now without question, but not the glass. In my experience glass matters more as long as the body is at least medium level quality and the EOS R certainly fits that bill. It’s not superb, but it’s not mediocre either. Glass matters, and glass is where Canon has always excelled. IMO better to wait for the pro body and use the best glass around than the opposite.
BTW I’m not trying to knock on your decision negatively, just giving my .02. I had a hard time deciding also. The good news no matter what side you are currently on, is that the competition is heating up which always results in a win for us consumers