S-expressions have been around since the 1960s. McCarthy was already proposing S-expressions for what XML would become, in 1975. Stop whining and finding excuses, and start using s-expressions.
I'm not trying to pick the best format for the job, I'm usually trying to pick the least bad one that's available IN the platform/standard library I'm using.
http://www-formal.stanford.edu/jmc/cbcl2/cbcl2.html