Ive tried other builds with Jax and nothing works as good as 21/9/0, generally ive needed mana regeneration on Glyphs though.
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you could go 21 in defense and 9 in offense. I havent really messed around with it but it could be nice to take away some squishyness. The offensive build is preffered though because you will have some close 1v1's and your dmg will most of the time make you the victor.