I agree Jax is higly UP but i think he doesnt need a lot to make him good, i think he just need that his ultimate scales faster or somekind of if actived ulll get max bonus for a few seconds then u lose ur passive until cooldown refresh, why? becouse may be 1v1 could be useful or in lane while u keep hitting minnions u can get in the fight full charged, but in a teamfight u need to hit like 4 or 5 times to start doing damage and by that time u are already death, and other good thing would be if u could store your stun longer, or taking the dodge out for activing it cuz average good players wont autoattack him, they would do skill on him.
Thats my idea he doesnt need more survability, he just need a rework in how his skills works.