Originally Posted by JohnAx

Too much like choosing a girlfriend for one answer to apply to all.

In my case I have ample supplies of AA miles and Avios but can't spend them. My usage patterns are too spontaneous for me to be interested in availability hundreds of days hence, thus usually nothing is available except "anytime" awards at a cost that sends me back to the full-price-ticket line.

Current availability aside, the uncertainty of future availability - on any carrier - suggests that spending flexibility is a paramount planning point. Along with picking a 'home' carrier that you'll buy enough paid fares on to obtain a status level that multiplies the miles you earn.