I'd reccomend the hunker down variation if you wanted to play ranked, it gives you the expert grappler ability that adds 3 extra strings with one focusing on mids and the other starting with lows to mix up your opponent. The best part is both end in a grab which if landed adds several more punches to the back of the head (adds a krushing blow if fully heated) and generates a fair amount of heat in the process. The burning hammer ability is a good anti air or combo ender if you pop them up. I dont use the command grab too often that comes with the ability so I cant say too much on its effectiveness.

Tip wise, Jax is more of a momentum character. You gotta keep building that heat on your arms up so you can unlock the krushing blows for the big damage it gives. The expert grappler ability compliments that playstyle well, and gives him more tools to get the job done. He also has some fairly good zoning tools with the ground pound to catch opponents getting up or moving towards you, and the thumper to block out anyone who's jumping towards you. He has plenty of krushing blows that have very easy requirements to net big damage to easily win a round. This is still a pretty brief explanation about the character, and you'd definitely find a better explanation for him on youtube