Wow...so barren.

Ive just started playing it, and its pretty good I got to say.(maybe not balance wise, but the plot is pretty good)

A lot of guide could be found here:
http://forum.playdom.com/forumdisplay.php?...nd-Guides-(MAA)

But I think the best iso no matter what is the health iso, which are the purple one.You might be able to work with the orange ones if you have a lot of tactician to boost your hp pvp bonus.

In later stages, the iso that cost gold will no doubt be the best, though you can only overlap either defense or evasion for the prismatic ones.
The red is for going super offensive, and the yellow for super defensive.At 45 points each slot, that is a whopping 360 points boosted.

http://avengersalliance.wikia.com/wiki/Iso-8