I leave it in hanks because it's less stress and pulling on the fibers. If it didn't come in a hank, I leave it in whatever form the yarn came in wether skein or ball. I toss it in one of my two 18-gal rubbermaid yarn totes to wait until I want to use it.
You're a great friend, but if Zombies chase us, I'm tripping you
i leave them as is until i am going to use them, then i make centerpull balls. i think i read somewhere that your yarn can get stretched if it is in a ball for too long the winding can sometimes be too tight.
I leave my yarn as I buy it, especially since I LOVE the way yarn looks when it's in a hank. I have these cloth bins in my closet which I keep my yarn in. I also have an unfinished wood treasure chest which I got at A.C. Moore. I keep all my unique and favorite yarn it it.
ON's: Water bottle cozy; socks in Knit Picks 'Frog Prince'; 4th pair of Bella's mittens
If you find balls much easier to store, I'd say just make sure it is wound loosely, maybe even too loosely. I wind from the swift, first time is tight, then again at least once from the centre-pull ball. But I like using my ball-winder.