Since we're on this:
DEF -60% or a second STR +1000?
Always def -60% over STR+1000. Always. Doesn't matter which kind. If the choice is between the two, then it's always def -60%. You really don't do jack shit with STR+1000. The kind of enemies it's even somewhat useful against are the kind of enemies that you could probably kill without STR+1000 and STR+1000 doesn't do anything against the really tough enemies that have defense up the wazoo. Def-60% means you don't even have to debuff enemies defenses all that much to be able to do crazy damage even to enemies with lvls in the several hundreds.
It gets trickier if you have to choose between the two -60% def traits. At that point you really have to think about your whole medal collection & what kind of medal it is. As has been pointed out, the ratio of ground & air enemies differs a bit between speed, power & magic so that comes into question especially if you don't have all that many medals with such traits, so you should have the one that most often helps you. But then... you'll still want to have both ground & air -60% medals for ALL colours in the long run because there will be situations where they'll come in handy.
That said, for the medals for which it really matters, it's not like you'll necessarily have to choose since they'll be rare and have two or more trait slots anyways, so there's room for both if you're ever so lucky to pull multiples AND get both -60% traits. Probably only ever relevant with tier4+ buffers if they only have two slots and you really want to keep Extra Attack as one (if you've had such luck to get it).