Defence just might be the best stat for all fighters, at 100% defence your fighter will likely be invincible because all incoming hits are reduced to 0. If this is truly the case then the second best stat would be meter gain, and third would be attack. In theory it's not that hard to obtain 100% defence, it would just be extremely expensive. Since a fully upgraded health/defence skill tree will give you 15% defence. The remaining 85% can be achieved by having 5 high level gold moves that each have a defence stat of at least 17%. Other stats at 100% like block proficiency and crit resist are basically pointless if you have 100% defence stat.