Legendary Free Ranger Base Upgrades
Free Ranger Damage Numbers
Legendary Free Ranger Wind Slasher Path
Legendary Free Ranger Tornado Thrower Path
Free Ranger Base Upgrades+ Storm Focus Path + Lightning Linguist Path
Up top, I don't think you can go wrong with either path. His Stormblades are so powerful with just the base upgrades, no one could fault you for enhancing his tertiary attack with Storm Focus. Going that route will gie you a great range to soften up enemies before heading in with Ride the Wind, or Stormblade attacks.
Wind Slasher basically just adds a combo to the base upgrades on the Stormblades...that said, it is an insane combo that deals tons of damage.
Ultimately, I would suggest Wind Slasher for rookie players and those looking for an easy and effective way to upgrade Free Ranger. If you are more of a defensive player and value range, go with Storm Focus.
For the bottom end you kind of have to pick your poison. Lightning Linguist offers a single lightning bolt at the START of Ride the Wind. Tornado Thrower shoots out a tornado AFTER Ride the Wind. Overall, the Twisters to more damage, but they are limited to a straight line...So if you don't anticipate the move finishing, or have it lined up right ,you could blow your chance...literally. Lightning Linguist is probably most helpful to beginners while Tornado Thrower will yield greater benefits to experienced players. That said, either path is cool and you wouldn't have me object if you picked one because you like the looks of it...