Im gonna try and describe my overall impression of both players since 2008. I knew ma long since 2006 and was a huge fan since then but ZJK overall explosive technique and character made me empathize more as a player.
ok ML fans are gonna start abusing me for this...BUT
ZJK is better overall regardless the result today, anything can happen I wouldnt be surprised if ma long wins 4-0.
Judging by their encounters from 2010 trials where ZJK breaked through against ma long:
My pov is that ZJK is more complete player in terms of overall technique, its not just the BH that varies so much but also his sneaky pushes and serves. He has stronger core and legs than ma long, probably dna + hard training from his father since age 4., He is definitely the best in close to the table explosive play both FH and BH, only FZD can match him on that game and possibly beat him convincingly on that aspect of TT
Ma Long relies on his tactics/fantasy flexibility and adapting to the opponent individually. He borrows his opponent's strengths and uses them against him, even in topspin rallies (thats not my conclusion but ZJK'S thoughts in an interview), definitely not as explosive as ZJK but he will be remembered as the most flexible FH in TT history.
Does not perform well under pressure, but he seems that his fighting spirit is much better now, the match against mizutani showed that, I strongly believe that mizu's comeback was much closer than it may appeared for a 4-3 upset.
All in all before 2010, zjk couldnt handle ma long's variation and got his ass kicked countless times (till then I think he only won one junior match against ma long in 2003 and after that ma long got like 10-11 straight wins in official matches, superleague matches counted also), after that game (2010 chinese trials) and of course being more confident ZJK found out how to neutralize ma long's opening play and took the initiative. In crucial points in important matches (im not talking about pro tours...) ma long was definitely more hesitant and ZJK knew this so he "trolled" him with serve receive many times and with his exquisit BH flick.
Ma long has a very good chance if he dont hesitates at all and just goes for it no matter the outcome, that is ZJK's mentality that brought him all the titles faster than anyone on the same technical level. Basically that's the mentality to reach the top, take it point by point and give it your best, nerves are normal, hell even ZJK was so eager to win in 2011 that he almost lost the 6th set against wang hao being 10-5 got trolled hard by wang hao to 10-10 but managed to break through.
Mentally ZJK is more solid and has already the experience of so many won close finals including olympics. I strongly believe that zhang A game is winning against ML A game hands down, results on important matches show that. But enough with the theory lets see what happens