Good windy's (half of these use hax, though so, meh)
Good trappers who mb a lot
I find that my javazon is quite dependent on good gear and my opponent not stacking. I don't think its a class that has many obvious mismatches and the outcome will often depend heavily on my opponents set up.
Smiters are a classic example of this. Most are easy and I love beating up on them, but switch in t-gods/wisp and turn on salvation and there's not much you can do except run and fury behind you hoping to deal phys dmg.
I mainly keep my javazon geared up because she is fun to play.