Hey there:)
Feral imo is better in most cases for open world in terms of survivability. This is due to a few things, first being the free instant Regrowth after spending five combo points via predatory swiftness passive. The second being that we have lower APM in our rotation, meaning we lose very little DPS if any spending the GCD to use the free Regrowth. The third being that we have two charges of Survival instincts, 50% DR is huge, albeit only 6 seconds, still very strong. Fourth, the Predator talent allows us to reset Tiger’s fury upon mob dying with with one of our bleeds on it. Fifth, we finally have an ability (primal wrath) that allows us to dump combo points in aoe scenarios! To top all of that off, feral is very mobile and loses very little by way of DPS in moving around. These are few reasons off the top of my head for feral being great in the open world.
With all of that said, Balance, when taking Nature’s balance talent will have more front loaded damage. Additionally Fury of Elune is also a great open world talent with good front loaded aoe damage. Balance is also considerably durable for a caster, and you can cast Regrowth in Moonkin form. This Regrowth cast, however, directly impacts DPS. Also, Balance has the passive chance to make lunar strike instant via Owlkin Frenzy passive (taking mele dmg I think). So pulling a few mobs and getting meled is oddly enough a DPS increase when this procs. Outside of this, balance while moving loses DPS, although mobility is still very good baseline, and even better in taking the Wild Charge talent.
Either choice is fine actually, you’re more likely to make it through sticky spots in the spec you are more comfortable with. To boot, the fact that Druids in general have access to the majority of the resto healing kit via resto affinity makes either choice ok as well. Lastly, I’d highly recommend getting familiar with all of the specs and use them to your advantage when situations warrant it.