The Laning Phase: Blight Stone or Quelling Blade?

Wondering if it's better to buy a Quelling Blade or a Blight Stone for laning purposes.

**Quelling Blade (200g):**

* Flat 40% melee bonus and 12% ranged damage bonus against creeps **only**
* Only increases base damage (white, not green number)
* Doesn't work against Roshan
* Can cut trees
* Builds into Battle Fury and Iron Talon
* Is 100 gold cheaper than Blight Stone

**Blight Stone (300g):**

* Reduces armor by 2 for 8 seconds upon hit
* Benefits from both base (white) and bonus (green) damage
* Equally effective for melee/ranged heroes
* Builds into Desolator and Medallion of Courage/Solar Crest
* Works on creeps, heroes, **and** Roshan
* Stacks with Orb of Venom

Now it is true that you can buy both a Quelling Blade and a Blight Stone for maximum farming potential, but early game that is both expensive and slot-prohibitive for some.

What is the ideal use-case for each? Blight Stone for ranged farm/harass, but QB for melee (unless they're doing more harassment than farm)? Buy both and sell QB later for the slot? Let me know what you think.