Yes, I like Jax. Yes, I may be a bit bias, take that into consideration. However, I believe this input still has something to add to the conversation of the champ.
I'd like to start out by saying I am appreciative of the consideration riot has given to Jax. The Guinsoos change hit him hard and he fell like a brick during the mage update. Jax's present win and playrate has seen a noticeable rise in the current patch thank to the buff. This recent buff in 6.11 has gone a ways to bring back the champ, yet I feel as if there is a bit more work to be done. The most impactful of the buffs was really good for him, the Trinity Force change now gives him an item to rush in lane and not feel bad about it. The attack speed for crit synergizes with Jax so well and the cdr lets him keep throwing out those devastating auto reset trades. These more than anything is the cause for his rise in sucess
Now we come to the direct buffs to Jax, the passive change. Lets be honest here. This was lip service for him. If the official reason is to be taken at face value and it was to compensate for stray cc, it seems really weak. First Jax is a spit pusher so, more than likely if you are in a situation where you have to team fight and open yourself to stray cc, you're doing it wrong. Second, stray is is almost always going to result in all of your stacks being lost anyway. Either the enemy is going to walk away and you lose your stacks, they focus you and you die/get chunked or they dont and you continue to either engage in a fight where your combat power may be decreased by half even though you are no longer ccd or you walk away. The vast majority of Jax's strength lies in his attack speed and his passive. Hit kit **needs **him to stack up his passive in order to dish out relevant damage otherwise he is a subpar champion at best and this is the rub.
As a champion that needs to attack stuff **prior** to engaging a fight to do damage his trading potential becomes very readable. He is going to walk up and auto minions before he goes in because he'll won't do damage if he doesn't. In lane this leads to the the infamous early game Jax power canyon, thats right canyon. Jax is so frustrating to lane with against any competent lane opponent. If you have the match up advantage they are going to let you push closer to their tower, you really have no recourse otherwise because your trading potential is founded on auto attacking minions to get your passive stacked. This leads to a lane that is free gold for any passing junglers. Yes, you have an e, but that cooldown last longer than the previous Ice Age, it isn't instant (has about a second delay before you can recast) and is limited in radius. You either spend a ward looking for the gank only to have it circumvented and you blow a flash OR you keep your ward so you can jump away and if you're good enough keep your flash but lose the visibility for the next gank. Going back to lane, your opponent now has the experience advantage (soaking up more creep xp while you ran away) AND the power advantage because so much of Jax's power is allocated in his passive. Now, with no stacks and wardless any advantage you might have is either neutralized or reversed.
Jax's power location in his passive is not really helped by his abilities all that much I believe that for a champion that HAS to auto attack, having abilities that synergize with it will go a long way._ If his Q added a stack (or two) of his passive it would instantly go a long way_. If adding stacks to his passive is not ok he is another suggestion: Give it a mini stun so we can get some auto attack in and thus stack out passive. A suggestion I have would be shifting a half second off of his E and giving it to his Q. It would be congruent with his live stun abilities while giving an ability infinite more synergy with the passive. That or some sort of slow would be nice. Another suggestion is giving the QW combo a stun and or slow or hell, give his passive some sort of slow, anyway to allow him to have the tiniest access to his locked power. One last ability that needs to be looked at is the E stun. Yes, it gives him a lot (aoe stun, damage reduction, dodge) but this has to be one of if not the longest basic ability coolldowns in the game. In addition burning your E cooldown is basically painting a bullseye on your butthole and bending over asking for the closest champ to chunk you out. Yes, there should be punishment for being outplayed into burning it, but if that is the case give it some more umpf.
E should be insta-castable that is no delay (if you so choose) between cast and stun and the stun should longer if you choose to hold it for the duration. That stun is weak sauce, you get in one and a half autos if you're lucky early game and it really is not worth just having it off cool down for the threat of using it defensively. If the stun duration is too much give it more aoe or let jax gain movement speed while it is activated in CONJUNCTION with an application of his passive. It would actually serve as the defensive/offensive tool in his kit it is supposed to be and actually be on par with the other tools available to his subclass while synergizing with the passive. "Riven: aoe stun, directional dash, shield/Fiora: directional dash, cc/damage immunity/ Ekko: massive aoe stun/shield, movement speed steal, slow, directional dash.
I think the critiques I bring up in this post have legitimate points that could be used in his future balancing. He is my favorite champion, but that does not mean I want to see him broken/contested. However, those that play him can attest to this just...lack. There is something missing from him, something keeping him from being a real Grandmaster at Arms.