How come you are interested in knowing? And of the ones everyone here is familiar with, what are you preferred textbooks for harmony?
For me to have a preferred textbook and to have a qualified opinion, I'd have to look at all of them. The textbook I used in college (by Allen Forte) I still use today if only for the keyboard patterns at the end of most chapters.
There is another thread here where I used a commonly used music theory term (scale degree) only to be called pretentious for using that term. I contend that it is a term that is commonly used and should be known by anyone studying music theory at a university level. I'm curious to know which theory textbooks are in use today ... and I'd bet serious money that all
the college level textbooks use that terminology.
The books I grew up with are Walter Piston's Harmony
and Allen Forte's Tonal Harmony in Concept and Practice
One of these days I'll copy all the keyboard patterns from Tonal Harmony in Concept and Practice and post them here. These patterns start relatively simply and keep expanding using material that is introduced as the book progresses. These keyboard patterns are to be worked out in every key and have made me a better player. It will take me an entire weekend to work through them all.