The recommended build is basically full AP, but she also has AD scaling (for AD or hybrid builds), an ability that applies on-hit effects and a massive AS steroid (for on-hit/rageblade builds), and her ult does %hp damage and gives a shield (for tank/offtank builds). Which build/builds is/are most viable?
I've had the most success with attack damage/on hit builds with tank gear to.
Warrior enchant/trinity force/deadmans/GA etc...
I don't play eve much, not a fan of her playstyle/kit, but when i do get her on aram for example I go a tankier build, 
and whatever boots.
with a build like this she's got enough survivability to not get instagibbed in the constant teamfight environment of aram, and because of the magic damage inherent in her kit she does great hybrid damage despite building only AD items it still comes out as ~2/3 physical 1/3 magic damage, heck I'd probably still use a similar build if I took her onto the rift because hybrid damage is always valuable and survivability helps you pump out more damage and stay relevant.
Back a while ago ad bruiser was big on her,
full ap, full ad, ap bruiser, and ad bruiser if still viable come to mind
i have nearly 800k on her i play her anything BUT AP its only good early game , you can have 25 kills and sink like a boat post 35 min its insane. She needs up front dmg for early and then needs to go tanky and have plenty of HP as the match goes on.
Proper order according to my personal theory build with her is
fighter <into< bruiser <into< off tank/ bruiser you transition and adept accordingly but you cant go glass cannon it just leaves her with no insurance
