This is completely anecdotal (and seems antithetical to the typical HN response to hCaptcha vs ReCAPTCHA), but I feel like I end up spending at least twice as much time trying to solve hCaptchas successfully because they have a lot less consistency in the objects you're searching for. I always have to zoom in to the modal and carefully search through each image, which invariably breaks whatever flow I'm in (moreso than other captchas).
For example, here's a screenshot from the hCaptcha website's "try it out" section [1] -- I barely recognized either boat in image #1 because it was so small. I missed image #3 because I didn't realize it was a huge cruise-esque boat (so big you can't even see any water) and I spent a good amount of time deliberating on #4 because, well, it looks like a car + windshield but... on the water? If it's a boat, I can't really tell, but I marked it as one solely because of the water in the background. Not sure if it was right or not.
It also seems to occasionally provide "find all the X" challenges without there actually being any X, which feels super cognitively weird ("am I just not seeing it?!").
I'd say ReCAPTCHA's main problem is deciding whether mostly-consistent objects being partially in-frame is enough to "count", whereas hCaptcha's main problem is actually recognizing the widely-varying objects in the frame. I think the former is a little more frustrating when you get something wrong, but the latter is mentally "harder" and takes more time on average, for me at least.
This is completely anecdotal (and seems antithetical to the typical HN response to hCaptcha vs ReCAPTCHA), but I feel like I end up spending at least twice as much time trying to solve hCaptchas successfully because they have a lot less consistency in the objects you're searching for. I always have to zoom in to the modal and carefully search through each image, which invariably breaks whatever flow I'm in (moreso than other captchas).
For example, here's a screenshot from the hCaptcha website's "try it out" section [1] -- I barely recognized either boat in image #1 because it was so small. I missed image #3 because I didn't realize it was a huge cruise-esque boat (so big you can't even see any water) and I spent a good amount of time deliberating on #4 because, well, it looks like a car + windshield but... on the water? If it's a boat, I can't really tell, but I marked it as one solely because of the water in the background. Not sure if it was right or not.
It also seems to occasionally provide "find all the X" challenges without there actually being any X, which feels super cognitively weird ("am I just not seeing it?!").
I'd say ReCAPTCHA's main problem is deciding whether mostly-consistent objects being partially in-frame is enough to "count", whereas hCaptcha's main problem is actually recognizing the widely-varying objects in the frame. I think the former is a little more frustrating when you get something wrong, but the latter is mentally "harder" and takes more time on average, for me at least.
[1] https://i.imgur.com/uyqvs5u.png from https://www.hcaptcha.com/