I totally agree, Jak's my main and he really does have a move for every situation hes in. Once you get him down he can definitely be an unstoppable force, his level 1 is pretty good and his level 3 is awesome. I wish his level 2 had toro's blast radius but until it does I never use it cause it's so avoidable. I barely see any Jak's online which makes maining him even more fun
My 2v2 partner plays Jak (who is a 110 BP Blackbelt 2v2). He tells me that Jak is all about being unpredictable and using tricks and gimmicks to his advantage. Just remember that his Square attacks (melee attacks) are pretty risky to use while on the ground (though be sure to make use of his mobility options such as air forward square, air down square, and air up square). Jak's Forward triangle is really good and his down circle is amazing. With Jak's down circle you can change directions while in the air, cancel out the attack while on the ground, or let it charge up for an unblockable attack. Don't neglect his forward circle either.