Preseason changes have been helping Sona so far; BUT
I still stand by my opinion that she needs a rework to add depth to her gameplay for both counterplay issues and champion fantasy.
As for what has been helping her:
Frostfang+ base mana regen buffs heleped her not go oom in lane as fast as she used to. Eye of the watchers frees up a slot that I hated using on just frostfang. Sheen costing less and Lich Bane having CDR helps her ap support build as well.
Windspeaker's Blessing +Runic Armor helps both her Support and AP Support bulids; Windspeaker helps Mikaels and Locket's actives as well I believe.
There's also the other option of a Keystone mastery. You can use Stormraider's Surge to go in with Crescendo, powerchord, and quickly get out, though you'll lose out on some healing since you can't get Windspeaker's.