Originally Posted by Asylumseeker
So ive been maining her a bit. My main method of playing her is going down the CDR route.
Thats pretty much core.
For my part, I tend to prefer Mercury Treads with Sona. Her damage output will never be particularly great, and getting out of CC faster (and the extra MR) will help you stay alive to spam your abilities. I also tend to prefer Tear of the Goddess to Chalice (and eventually AA Staff, and with lower CDR you'll get that max mana quicker), but that may be more of a personal preference.
Other ways to play that im not sure how viable.
AP - Seems interesting but not massively powerful, but could be good with lich bane
Tanky - Not tried it myself. I can see how it would work, but then your pretty much a poor tank with some support.
Aura - Not really much use apart from carrying around items like Aegis.
DPS - I tried this a bit, did lots of damage but told it was a useless build.
AP can work, but her scaling is not great on her heal, and thus is best to add additional damage if your team is lacking it. Though, at that point, I personally might recommend choosing another Champion instead (if available).
Tanky is a bit of a misnomer. It's really about just trying to stay alive, and means buying a few more Armor/MR items rather than CDR or AP items. You still won't be able to initiate, though you can bait. Soul Shroud, Aegis, and Reverie are all "defensive" items that lend to survivability, and, in my opinion, make for being very good items.
Aegis is good regardless, and fits into the increased survivability ("tanky") build, but works decently alongside CDR and AP builds as well as a defensive item, particularly if you play "back" more and don't leave yourself open to attack too much (which is ideal anyway). Likewise with Soul Shroud, though obviously that's best with a mana-dependent team. Spellvamp can also help with Will of the Ancients, and obviously helps the more aggressive AP build, and a Magic Damage dependent team. I would never bother with Stark's Fervor on Sona. Obviously, if anyone else has already built an aura item, building another is fairly questionable.
Like Stark's Fervor, I see little point in building AD on Sona. She has no "steroid" abilities other than her Q's aura to improve her damage (which is a relatively small gain being an aura), but her level gains to attack speed are atrocious, and more importantly, her attack range, mobility (even with E) and survivability are generally much lower than other ranged AD, and the gold and item slots could have instead improved her Q and R, which at least have decent range on them.
It can be done, but it can usually be done better with an entirely different Champion, and doing so reduces the effectiveness of what makes Sona good in the first place.