Just to add in case you’re not aware, the EF-RF adapters are literally just spacers that shift the lens mount to where it would have been if there was a mirror in there - optically it’s just 24mm of air, so no quality impact at all.
The only thing to keep in mind is that there is a slight autofocus slow-down with the much older lenses, but not enough to bother me.
I literally just faced this same dilemma! I went online looking to upgrade the kit lens I’ve had on my Canon EOS 70D for nine years and got sucked into the mirrorless hype.
In the end I sortof ended up upgrading both… I got a great deal on a second hand Canon mirrorless body, and because it has in-body image stabilisation I could then spend a lot less money to get a 25 year old ‘L’ series EF lens rather than a newer one with IS in the lens.
I’m extremely pleased with this set-up so far, and even more pleased that I can add to my lens collection in future for much less money than if I needed IS hardware in every lens.
This video of one of the rioters getting repeatedly struck with bricks thrown by his own mates is well worth a watch… Or two… Or three…
https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.mirror.co.uk/news/uk-news/watch-rioting-southport-thug-bricks-33362943.amp&ved=2ahUKEwiglLKFltGHAxUjRkEAHThnAI4Q0PADKAB6BAgSEAE&usg=AOvVaw0uamrR8Do7LsyZ53ECNnN5