I'd say improve your Busa. Why invest time and effort into a character and then drop them? I like the way you fight with Busa too. Never seen your Jacky so I can't give my opinion on that matter.
Join the #YEAAAAAAAAAAH Army.... we are waiting mwahahahahahaha >:3. Lol no but seriously, stick to Busa. There has been instances to where i wanted to drop Jacky myself, but i stuck to it. Now i can pull off FSK like a pro (Goes back to dropping it continuously) lolol. If you want.. you can check out the jacky general discussion thread.