There's no right or wrong answer here, only what your priorities are.  The Current setting will make AM check the current values at Whattomine, and the 24 hour setting will make AM check the 24 hour values at Whattomine.  AM is agnostic in this decision... it's yours to make.

Why would you choose one over the other?  Using the current values will attempt to keep you on the most profitable coin... at that point in time.  This can and will cause peaks and valleys in your overall profits because coins don't stay "most profitable" for very long.  The 24 hour values will help smooth out those peaks and valleys to keep you mining a "mostly" profitable coin longer.  I've written extensively about profit switching in this thread, I ask that you go back or search this thread for my musings and opinions on the matter.

Remember though, the Current and 24 hour setting would only apply to individual coins that you are mining, not to Online services like zpool, MPH, and the like.  If you setup a dozen of your favorite coins as individual pools and put them in a pool group then AM can profit switch on that pool group and will use the Whattomine statistics including your Current/24 setting to help AM decide when to switch.