From my experience, and considering I have been in the industry since before parking programs (4000+ domains), there are only 4 programs worth consideration
SEDO (google feed)
PARKED (yahoo/bing feed)
TRAFFICZ (yahoo/bing feed)
DomainSponsor (google feed)
Now you also have to consider origin of traffic, each programs has its pros and cons..
if you need referral then PM me and I will send you a link.