Which ring for a Dragon Knight?

ignoring the 3 str and dex from the lilin since it doesn't come close to equaling 1 att.

I'd say that is fairly wrong.

Like just for example.

My range, 3 atk ring: 2970-7479
/ adding cruel ring's critical rate makes this equivalent to 2975-7492, because crits suck for Paladins
My range, 3 atk 3 str 3 dex ring: 2985-7512
My range, 4 atk ring: 2986-7520

So the difference between 3 str 3 dex, and 1 atk, is 15-33 vs. 16-41 added damage (cruel ring adding 5-13). Or more directly, the Lilin's ring is equivalent to 3.8 atk.

Tack on MW and the gap is a little larger
3338-8426 -> 3353-8458 vs. 3355-8471 (15-32 vs. 17-45) but it's still worth more than 3.7 atk.