Lethal Hunter (+ Adv feat), First Strike (+ Adv feat), and Favored Enemy class talents all work with melee attacks and (if used properly) would allow your first attack at a chosen enemy to crit on a 12 die roll or better, then the rest the fight could be 14, 15, or 17 - again with proper planning. But I'll admit such a Ranger build is kind of a one-trick-pony, focused only on melee fighting. And it would be 5th level before all this worked against humanoid enemies.
But if you want a melee fighter who uses Dex instead of Str, you might want to look at the Druid Shifter and/or Warrior Druid builds. Don't let the class name fool you. A druid can be built to be a tough fighter with no spell casting ability at all. There is the small baggage-type issue of turning into different predatory animal shapes if you want to be particularly deadly, At Will if you're an Adept, but other than that it's a Dex based melee fighter.
And Rogue (as mentioned above) is not a terrible option either.