Shuffle is the best in most scenarios. Snares are everywhere. Shuffle is your friend. Also, unless you have high magic regen, you'll want to save your magic for fearing.
While Shuffle is more useful in most situations, I like Double Take (morph of Blur) in IC for the speed buff. If you're using a bow you can keep your resources topped off while keeping Major Expedition up 100% of the time by alternating between dodge roll with bow and Double Take.
For a pvp stamblade, Shuffle is usually a better option over Blur due to having a limited magicka pool. Some builds can take advantage of Blur to its fullest and conserve the stamina, but in a fully-dedicated offensive stam build, you'll probably want Shuffle.