Which ring for a Dragon Knight?

High level warrior friends being who exactly as the second standard? Anyone short of Coen, Jasper, or Fran, I wouldn't take their advice. Also I feel I should note that both Dusk, Stereo, and Noah are far better mathmeticians than myself (seeing as they contribute the most to the DPS tables. Dusk specifically).

Justin had me rep his hero (eDating) at oblivion 4 a few nights ago and I noticed was doing crits so I checked his equips and he had the cruel ring. I asked him which is better and he said most heroes and drks he knows got the cruel ring. So I jumbled around with calculations rounding my range to 9000~20000 and 8950~19900 and ignoring the 3 str and dex from the lilin since it doesn't come close to equaling 1 att.

 Spoiler

normal = 340% at 0% rate for crit
cruel = 380% at 5% rate for crit
crit = 360% at 10% rate for crit
SE = 620% at 15% rate for crit
cruel + SE = 660% at 20% rate for crit
crit + SE = 640% at 25% rate for crit

9000 ~ 20000 apple'd = 48960 ~ 68000 at 0% rate for crit
9000 ~ 20000 apple'd with cruel = 54720 ~ 76000 on crits at 5% rate for crit
8950 ~ 19900 apple'd with crit = 51552 ~ 71640 on crits at 10% rate for crit
9000 ~ 20000 apple'd with SE = 55800 ~ 124000 on crits at 15% rate for crit
9000 ~ 20000 apple'd with cruel and SE = 95040 ~ 132000 on crits at 20% rate for crit
8950 ~ 19900 apple'd with crit and SE = 91648 ~ 127360 on crits at 25% rate for crit

Basically the minimum kill time for bigfoot is lower on the cruel ring but the maximum kill time is higher. The average kill time with the crit ring is better, but the potential lower--same goes for other bosses. The thing that still bugs me about the crit ring is that I'm obsessed with trying to beat my own kill times. If you say getting the crit ring is a better choice, I'll take your word for it. I suppose when it comes down to damage output on boss runs with friends that's what matters most anyway. I just realized coen said to get the crit too in an earlier post and I think he's probably the most knowledgeable hero on kradia, so that about makes my decision final. Crit it is.