Well it depends.
If you havent already have a deck of 5*, then getting a few more to complete it would be good decision. of course only get the decent ones, not the old bad type guardians.

Stoning your Gilgamesh would means adding quality into your existing deck, but I hope your gilgamesh is a good type like fast or int at least. Otherwise, try upgrade your gilgamesh to a better type. Fully stoning a guardian requires around 25 stat stone (iii) which is costly. With that much you could get one good type guardian or two average type guardian.

LS>QS combo is good, but not necessary the best. Having some individual player like Ettin, Shiva or S. Banshee can be just as good as any QS/LS cards.

Interested to see your current deck and whats your wish list for the current goal.

10 hours... and no trade response. I can't do any trades today.
Perhaps... it's a Friday, so can do after working hours
Yes.

I think I'll give priority to those that at least no full 5*, this sounds better?

Let me discuss with fallenout and negisf then it should be fast enough to kick start