I would suggest doing some research and hitting up a reputable shoe store. Start by reading these:
Choosing a Shoe: The Very Basics - Runner's World Shoes &
How to Choose Running Shoes!
As a general rule, I would stay away from shoes with air cushion, especially in the heel area. Any type of uneven cushion can cause too much calf flex on impact and lead to early cramping.
Personally, my favorite brand is asics although they tend to wear out quicker than other brands. The perfect brand or shoe will change from person to person, so just buy the pair that works for you.
*Also, stay the fuck away from cross-trainers. Buy a shoe for the specific activity you plan to use it for.