So I've been doing a little experiment. The gold gacha has a daily special that is only 150 gold the first time each day. So over the past few days i've been experimenting with it to see what i get. So far this is my results:
1. R- Weapon
2. SSR- Ouroboros
3. SR Eido +1
4. SSR- Ouroboros
5. SR-Kamihime Weapon Oberon
6. R-Weapon
7. R-Kamihime Weapon Circe
8. SSR Eido- Behemoth

So yea i'd say that's been pretty good so far. My original idea was to use about 3000 gold, the equivalent of 1 gold x10 to see if it's worth it as you aren't even guaranteed an SR from the daily unlike the x10. So far it looks like i'll be doing the daily for a while.