What about the VT-4 is better apart from the RWS which the 99A can be upgraded with? Same goes for APS.
For egs the VT4 uses a full-electric gun control (for domestic tanks not available until Type 15), a more digitallized fire-control system and to my knowledge a better bus system than the CAN. (I might be wrong with this one tho) Plus the new VT4s use a better powerpack (w/CH1000B transmission compared to CH1000A on the 99A, both newer and more advanced, and there's no need to remove the pack out of the tank to change its power levels) The turret of the new VT4 is also better designed in terms of protection shapes (gosh it's both designed to be better looking and more effective. Norinco asked artists to help design the tank just to make it prettier (lol)) The 99A's turret is both too high and the protection of the upper part of the front of the turret (the sloped bit) decreases rapidly. The new VT4s use FY4s both on the turret front and frontal glacis, plus on the turret top that makes it more immune to EFP projectiles. I think the only thing VT4 lacks compared to 99A is aan improved gun (VT4s use old ZPT98s which are even non-extractable (I remember the 99 is extractable (which uses the same gun as the VT4)), and use old anti-recoil mechanisms.), access to a better armour piercing round like the DTC10-125 (VT4s only have access to BTA4s, which is equal to the DTW-125 for domestic use), and an anti-concrete round as equipped on the 99A, a laser sight suppression system, and several pieces of FY5s. So overall it might even be better than 99A, except that it's not as balanced between the four aspects of Firepower, Protection, Mobility and Informationallization.