I just finished watching two Hana Kimi versions, one starring Ella and Wu Zun (Taiwan) and one starring Maki Horikita and Shun Oguri (Japan)
Although both series proved to be really entertaining in their own rights, I believe the Taiwan version edged out a bit over the Japanese series because 1) the storyline and sequences made more sense) 2) the comedic scenes were funnier 3) the actors had better chemistry, mainly due to Ella, who simply shone in her role as Lu Rui Xi, the number one fan of Zuo Yi Quan, a former high jumper who quit the sport for unknown reasons. Jiro Wang who played Xiu Yi also made a strong impact with his role which contributed to the level of energy of the series, sustaining it until the end.
The Japanese version, although it retained the feel of the original manga, was more sober than its Taiwanese counterpart. Most of the scenes that should have been funny fell flat probably because Maki seemed uneasy with her role as a girl disguised as a boy in Osaka High. Shun Oguri, on the other hand, fit his role to a T. Tohma Ikuta was also not bad as Nakatsu Shuichi, although there were times when he thinks to himself for long periods of time while he gestures around wildly which kind of gets to your nerves once in awhile.
So who's your bet? Taiwan or Japan? Your call