TAN, but you'll need a VOA for comparison.
Save the TBN for engine oil.
Excessive wear and shearing are things to look at. 25% loss in visc is a reason to flush the atf. Wear is transmission dependent. 100ppm per 30k or less is a goal.
Insolubles and those wear particles, will chew into all your seals, clutches, and help carve into soft metals.
Antifreeze means your built into the radiator ATF cooler is leaking. Excessive water could mean you need to spend less time offroading/snorkeling thru the local river.
What it comes down to is your transmission type, driving style, weather patterns, fluid used, and any 'mods' to the filtering, cooling, shift patterns, engine power......