Which one would be better...more attack speed or more damage on a thunderfury? Overall dps on the weapon is higher with IAS but since the proc is based on weapon damage, wouldn't that be better?
Really depends on whether you got a black damage roll or not at the moment. If you have black damage DAM wins, if its an elemental roll (that you can't reroll to black) then IAS is the right choice.
Well obviously since it always comes with lightning damage and you're asking about re-rolling IAS vs ED (enhanced damage, it's the more commonly used abbreviation for what you describe DAM%) it means your weapon is not and will never be a black weapon. Therefore, right now IAS will definitely be better than ED. However, once this will be fixed ED is better.
However, there's no word about any ETA of that fix (or if it's gonna be fixed retroactively at all). You might regret it in a couple of weeks if they fix it and you chose IAS; you might regret it if you chose ED and they never fix it. Or it won't matter because you might find the Wand of Woh tomorrow ;-)
Well obviously since it always comes with lightning damage and you're asking about re-rolling IAS vs ED (enhanced damage, it's the more commonly used abbreviation for what you describe DAM%) it means your weapon is not and will never be a black weapon. Therefore, right now IAS will definitely be better than ED. However, once this will be fixed ED is better.
However, there's no word about any ETA of that fix (or if it's gonna be fixed retroactively at all). You might regret it in a couple of weeks if they fix it and you chose IAS; you might regret it if you chose ED and they never fix it. Or it won't matter because you might find the Wand of Woh tomorrow ;-)
Right now I'd go IAS.