From 3.4.3 to 3.4.6, no more new features added in, so there shouldn't new potential bugs involved in. From the logs below, there are bug fixes, optimizations, other enhancements, which means they keep fixing bugs, optimizing, so in whatever aspects, 3.4.6 should be the most bug-free, stable version out of 3.4.3, 3.4.4, 3.4.5, 3.4.6. I will take one as base to develop, before take action in case I missed some important information about the change, want to consult other developers who are more familiar about the changes in different versions that is there any reason I shouldn't choose 3.4.6? Thanks a lot for you answers and comments.
version:3.4.3 August, 2018 OpenCV 3.4.3 has been released, with further extended dnn module, documentation improvements, some other new functionality and bug fixes
version:3.4.4 November, 2018 OpenCV 3.4.4 has been released. This is a mantenance release. New features are landed in OpenCV 4.0.
version:3.4.5 December, 2018 OpenCV 3.4.5 has been released. Bug fixes, optimizations and other enhancements are propagated into OpenCV 4.0.1.
version:3.4.6 April, 2019 OpenCV 3.4.6 has been released. Bug fixes, optimizations and other enhancements are propagated into OpenCV 4.1.0.