Just seeing this thread, so a little late to the game. I shoot a Zeiss 50mm on Sony a6600 body, and went through the same decision process. I already own the Canon 60mm lens, but got bogged down in picking an adapter + ports for Sony/Canon and went with the Zeiss 50mm instead after finding a pretty good deal on eBay.
Overall, I'm happy with the lens. Guessing I've had it in blackwater on ~10 dives off south Florida and one in Indonesia. It does best in blackwater with lots of focus light and the aperture set to a pretty high number with high ISO, shutter around 1/125s. Not ideal compared to results I see from local Nikon+60mm shooters, but it does the job and is reasonably quick for focus with enough light (either red or white). A recent blackwater example is here. Looking at a possible upgrade to Canon R7 with 60mm macro to help with blackwater, but that's a different topic.
I used this lens extensively on a recent trip to Indonesia, see this gallery for a variety of macro shots taken with it. I found it relatively easy to shoot normal macro subjects with it, especially compared to blackwater.
One thing I haven't seen mentioned is using the Zeiss 50mm with wet optics. I found that a CMC-2 on a flip adapter was really useful to get in tighter where field of view was less of a concern, and it gave good results. Tried it out for the hell of it, and it's on my camera for any non-blackwater macro dives with that lens now.
Hope this is helpful.
Lance