Just a short note. After spending 10 days comparing the two, I prefer PSvue over Sling.
This really comes down to personal preference. They both have very similar channel lineups and neither has a very good user interface. For me, PSvue came out on top because of the better DVR like experience. More shows were available with the Pause/FF/RW feature.
For now, at least, the subscribe/cancel process is fairly easy and switching between services only takes a few minutes. So these decisions aren't chiseled in stone.