Mirror is stinky garbage for Resto (and Haste is pretty meh for us in general), so my instinct is to say go Velen's for now. I am a big fan of Jonat, though.
An easy way to test is to try a little of each, look at logs, and compre roughly how large a benefit you're getting. You can estimate the Jonat's benefit by taking your count of HW/HS casts (*10% per) and multiplying that by your average CH (not perfect but will get you in the ballpark). My gut says if you're using Velen's effectively it's probably winning, at least in a raid situation.
If you could get Cake or Map or a stat stick (preferably crit with your current stats), then definitely the ring. For the standard shaman build/game play, Jonat is BiS. Mirror is just so disappointing for us that I'd recommend using Velen's until you have a different trinket or your research finished.