Lugia level up

Attack iv must be 15
Def iv is least important

You should go for #1 if iv A/D/S listed above

Lugia is not an ideal attacker, I have a hard time believing it makes any difference. Pick which one's moves you like better.

Moveset?

The 93% IV Lugia should be the obvious choice here. Higher IVs = better stats. Then again, if you can find a better IV Lugia than your 93% Lugia, I'd say hold off until then.

I feel that the difference will be insignificant in practice. In the raid meta the 15 attack should perform SLIGHTLY better, but unless you happen to just cross the threshold for greater damage on your quick move, then it will not really be noticable. So if you like the idea of powering up the 93% more, then go ahead.

The iv 93's.
Absolutely.