It really depends on your network infrastructure and your internal policy. Here are the difference between Transparent mode and Explicit mode. Hope it helps.
Explicit mode:
You need to configure proxy at each browsers at each end point which making authentication simple as HTTP standard code 407 is specific for proxy authentication.
Transparent mode.
You need to configure either PBR or WCCP at your network device without changing anything at your end point. However it will make authentication a little bit complicated.
Please mark my reply as correct answer if it helps you.
