If this thread was simply questions like those, I'm sure people would be more than happy to answer them. I can take those two if you want:
Ace's/Askar have pretty much no use any more, as the current state of the game has nullified the need for any significant amount of Accuracy gear. In the rare case where you may not be capped at 95% Accuracy on a given mob, changing food from Bison Steak to Marinara Pizza +1 is still significantly better than changing your gear to emphasize Accuracy. Walahra turban, or any higher Haste head will handily destroy Ace's/Askar.
Zelus Tiara vs AF3 helm with 6% Haste and other stats, assuming capped haste in all slots either way: This is a more complicated question that I cannot answer with certainty without being told what job we're talking about, inside/outside Abyssea, and what two full gear sets you're working with. As a general rule, I can say that you should look at what Haste gear you can replace when you go from AF3+2 to Zelus Tiara. If you gain more powerful stats in those now-free slots than you had on your AF3+2 head, then Zelus Tiara should have the advantage. If the stats you gain by freeing up haste slots are less than what you had on your AF3+2, you are probably better off with your AF3+2.
This is assuming that you were capped on gear haste with both sets.
Edit: @Rog, what NM and job combination (capable of using Ace's) may still have low enough Acc with Pizza+1 for Ace's to overtake Turban? Serious question, I didn't think there were many still out there.