FS1
But let's be real, ESPN is the most valuable
ESPN currently charges cable providers ~$5.15 monthly per subscriber, according to Reuters.
At launch, Fox Sports 1 is charging $0.23 monthly per subscriber, according to the Sports Business Journal. FS1 originally wanted $0.80 per subscriber.
There are good reasons to believe FS1 is going to succeed (and thus raise their subscriber fees). They have the broadcast rights to live sports people care about, they've made some smart hires, and there's a ton of money behind it.
But this is the initial gap between the two. Fox has a mountain to climb:
Tony Manfred/Business Insider