Look, I am not an expert, not even a decent amatuer on tanks. But looking through your guys' arguments, I can pretty much have a good idea which tank is possiblely the best in Asia based on several basic but important principles.
Likely candidates are 99G (99G-a2?) , K2 and T90s of Japan. So? One does not need to be an expert to judge.
1. Everyone knows that the best warplane is F-22A. The main reasons are its stealth and cruise functions amongst several others. However, if without stealth and cruise, do you still think that F-22A is the clearly the best , particularly in light of its outragous price tag, even tough it might has slightly better radar, electronics? Probably no...
2. The same as warplanes, except K2 can clearly offer some revolutionary techs which other don't have(aka steralth in F-22A's case), which clearly it doesn't , its price tag as the highest of all tanks has already shown that it is likely not the best. It is because tanks are not sport cars in which one solely collect names such as Ferreri, Porche for their exotic charateristics and some particular functions to argue which is the best. Tanks on the other hand are just tools, indeed mass tools of warfare, in which (1) mass production cost and (2) 100% domestic manufacturing and maintanence capabilities are almost the same important parameters of judgement --- as its amour, main gun, speed, maxi functioning areas,etc.
It makes absolutely no sense to produce something out of reach of (1) and (2), even in exchange for a slightly better individual function/s in other areas, as in war time when tanks are put into use, one can not afford the risks of not being able to mass produce it as desires due to its high unit cost , and /or having no gurantee to be able to accquire sufficient supply parts in international deals.
In an extreme analogy, if one can somehow produce a "KING" tank, 100 million per unit cost, with the NASA speceship-alike amour, etc, can we say that this is the best tank in the world? Don't be ridiculous! With the same unit cost as K2, as one memeber said earlier, Chinese ventors could likely come up with its killer and more.
Due to these 2 reasons alone, without looking into the details of K2, I can roughly dismiss it as the best.
3. Most importantly, to produce a top of line tank requires a full spectrum of techonologies across fields. That's the fundamental reason why why India's arjun fails. It is because India's overall reaseach/design/material science/heavy industry manufactoring capabilities havn't reached the level required yet!
On this note, I am reasonablely confident that only China, and Japan in Asia have this level of OVERALL capabilities to produce some best tanks, or ships, or airplane, due to the same logic. Not Korea, sorry. Even though Korea might be more advanced than China in certain areas, it definitely can not beat China in the full spectrum. Even with extensive foreign help as K2 's case , to intergrate various techs requires hollistic level of knowledge and capability in which Korea is not at top 2 pecking order!
Don't get me wrong, I am not underestimating K2. It might be a very good tank. But the best in Asia in reality war time enviroment? NO way! But it might be one of the top line "sport car" in a showroom.
Therefore I think the battle for the best of Asia is mostly the game between 99G-a2 and the latest Japanese MBT. Both countries has roughly similar level of overall capabilties, with Japan still probably having the upper hand in general. But China is rapidly closing up the gap!
Tanks, unlike ships, are tricky too. It is because environment in which tanks are put into use plays also a big part.
Which one is the current best? I don't know according to my knowledge given China seldom shows off the best functions of her leading weaponaries. The best could be either of the two in reality.
