I actually finished my omnilex novus already. http://eu.finalfantasyxiv.com/lodest.../blog/1319292/

I went with crit and accuracy. The accuracy is because I spend a large amount of time in second coil adding damage, and while determination increases both your healing and your damage, accuracy is easily the largest damage increase stat you can get... And my heals were powerful enough anyway.

Most importantly to me is that it realistically allowed me to hit the accuracy cap with a minimal amount of melded gear, which as a healer adding damage is important, since it's frequent where I only have a couple GCDs to spare, and being able to rely on all my spells hitting during that time is very good.

Eventually I'll get another weapon anyway, but my relic will forever provide me with something to swap to with a lot of extra accuracy in case I ever do content for which it's 100% vital as opposed to just a damage increase to have no chance to miss.