I've never had much luck with these things. Maybe its because I am a trademan and as such my fingers are often rough or dirty. Sure I've done all the usual, enroll different fingers, do the same finger several times but can't say it helps. I have tried Huawei and Samsung, Samsung are the worst. On my S10+ it works roughly 1 out of every 4 attempts. I really miss the bog standard finger print readers, never fail or let me down.
I agree.
Capacitive fingerprint sensors are still the gold standard. Huawei especially did an excellent job on theirs, at least on the View 10 that I had. It's super fast and never missed a beat.
For optical sensors, by default, they are already slower than capacitive. Basically the phone has to light up the area first before the sensor can take a picture of the fingerprint. The early ones definitely had issues, and I do agree that Samsung's early ones are notoriously bad, definitely worse than what others like Huawei did. (again, I mentioned Huawei because I simply see they did an excellent job on their implementations). Having said that, recent Samsung ones are getting better. My A71 is not bad. It's obviously slower than a capacitive sensor, but accuracy is a lot better than some older Samsungs I've tried.
I have no experience on the sonic ones, so can't comment on that.
If fingerprint is not ideal for you, try the face recognition. Obviously it won't be as secure as FaceID on iPhones, but at least it's something. I use working gloves when I work, so I use face recognition on my Samsung, and now am trying Bixby for the things I do with the phone.