Donate for STS, Falin'rush, or Oathbinder for Hunter?

Hey, so my hunter is about to hit 80, and I'd like to do decent in raids DPS wise early on in my gearing career.

I am doing two specs (which both use all 3 of these items BIS anyways) BM for more relaxed raiding and MM for when I want to tryhard

I'm wondering which item would be the most practical to get at level 80, between STS, Falin'rush, and Oathbinder in order to get highest DPS when I get into raiding (as I won't be getting any of the three items in LK 25 HC or Halion 25 HC for likely a long time)

Let me know, thanks guys!

The crossbow should be your first buy. It contributes the most to your dps compared to all other items.