If I had an owner with cash I'd go with ESPN. Not a big fan of them since all they seem to have on these days are in house people but it's got name recognition with listeners and advertisers, so if people knew you were the ESPN Radio station in the market when listeners heard mentions across the 8 or so ESPN platforms, then you could get listeners and advertisers to offset the costs.
If I had an owner with no cash and wanted something totally free, Yahoo is where I'd go. I'd stay away from Fox because it has nothing, other than a name, attached to Fox and you're dealing with Clear Channel. I only want to deal with Clear Channel when it comes to their high profile syndication like AT40, Limbaugh, Beck, etc. Now if FSR was actually related to Fox Sports then it'd be another situation...