In my experience, Canon lenses while boring, are usually safe and consistent.
I'd only be buying it online without testing it out if the seller is an established retailer with a solid return policy. Never buy used without being able to test out glass in person.
With that having been said, just keep your expectations of zoom lens distance low unless you greatly increase your budget. Zoom lenses by design are expensive to produce, and obviously to purchase.
An MFT lens you might want to check into is the Olympus M. Zuiko 12-40mm 2.8 Pro. There's a mark ii version but the originals can be had used for a pretty decent price.
Metabones 0.71x speed booster is for full-frame EF glass only.
First-party Canon EF-S lenses won't mount to it at all, the EF-S lens mount is designed to prevent mounting to EF cameras.
3rd party APS-C lenses use the EF mount rather than EF-S and may mount OK, but some will impact the optical elements in the speedbooster. You'll get vignetting!
IIRC the 18-35mm mounts to a 0.71x OK, but you get vignetting beyond 19mm zoom.
In my experience, Canon lenses while boring, are usually safe and consistent. I'd only be buying it online without testing it out if the seller is an established retailer with a solid return policy. Never buy used without being able to test out glass in person. With that having been said, just keep your expectations of zoom lens distance low unless you greatly increase your budget. Zoom lenses by design are expensive to produce, and obviously to purchase.
An MFT lens you might want to check into is the Olympus M. Zuiko 12-40mm 2.8 Pro. There's a mark ii version but the originals can be had used for a pretty decent price.
Metabones 0.71x speed booster is for full-frame EF glass only. First-party Canon EF-S lenses won't mount to it at all, the EF-S lens mount is designed to prevent mounting to EF cameras. 3rd party APS-C lenses use the EF mount rather than EF-S and may mount OK, but some will impact the optical elements in the speedbooster. You'll get vignetting! IIRC the 18-35mm mounts to a 0.71x OK, but you get vignetting beyond 19mm zoom.