destro dont need all the 30% of the haste, its a good thing to have +1 immo tick, but sometimes ~20-25% haste is enough.
i like to jerk on the stats so im going for the 30% just because i want to lol.
98 spell pen is TOO MUCH in my opinion, 70 is good for like soft cap.
undead mages dont have more fire resistance than 70.
as myself id say get 30% haste, go full int with resil soft cap (31.50% if im right), and get t6 second bonus.
but as affli you have to get 30% passive haste and the full int soft cap resil things (you dont need the t6 2nd bonus there, even if you can crit 5k Sbolt), so you can proc for 20% more haste from the corruption and 50% haste is amazing (dots tick like omfg crazy damage) and you can cast things extremely fast.