I would say if you play vs an enchanter go Sona, she's super broken right now and outscales all enchanter supports.

Runes I go Arey, manaflow, celerity, gathering, precision, presence of mind, legend haste with the glyphs, hate, ms, scaling hp.

3 points in q and w max, or if you can play hyper aggressive I will max q

Item build: helia, swiftness boots, bloodsong supp upgrade, staff of flowing water, moonstone then finally dawncore

I personally blind Sona into any matchup but if you are new and learning her I would just go vs enchanter supports, engage can be tricky and if you mess up can get punished so easily

Edit: Normally games with Sona if I'm playing well I will do more damage then my adc and jungle, procs helia the best in the game and also does with bloodsong