Fafnir weapon VS SW weapon

So my bowmaster is almost at lvl 160 and i thought about getting new weapon but i'm not sure what to do:

Fafnir Wind Chaser:
Attack Speed: Normal
Str: +40
Dex: +40
Weapon Attack: +160
Accuracy: +120
When attacking bosses, damage + 30%
Ignore monster defense: + 10
Upgrades Available: 8

Sweetwater Bow:
Attack Speed: Normal
Str: +45
Dex: +45
Weapon Attack: +160
Accuracy: +150
Speed: +12
When attacking bosses, damage + 30%
Ignore monster defense: + 10
Upgrades Available: 7

Terminus Stormchaser:
Attack Speed: Normal
Str: +40
Dex: +64
Int: +0
Luk: +0
Weapon Attack: +169
Accuracy: +200
When attacking bosses, damage + 30%
Ignore monster defense: + 10
Upgrades Available: 8

- SW bow is less expansive than faf wind chaser
- with faf weapon i get 60% boss damage (set effect) while with SW bow i get only 30% (I'm not bossing alot but i try as much as i can)

I got 2bill mesos on me so what should i do?