Luck does not mathematically exist, when you search the best optimization available, you do math. You need a damage formula, and you normalize crit on it to get your average damage. Because
If you got a better average damage with +21crit than +15dtr, it's mean the dtr monk will be more often behind the crit monk than ahead.
I rely on the work of a guy who seems to have a mathematics level well above average and who has found the most accurate damage's formula known to date.
http://valk.dancing-mad.com/?page_id=179
If you want something more accurate you can try to refine his work since he posted everything.
I think it's still better to rely on a 99% accurate formula than absolutely nothing or on a "dtr is better because of RNG", just no, it can't be so easy.
I would sayit depends of your progression.
If you just started coil, you can loot legs, ring, and earings on the first turn.