hell i've had no problems with cogent, even on a rackshack box.. even though cogent and rackshack both have wavy reputations, neither have fucked with me so far. i'm looking at a cogent 100mbit feed for $1000 myself
uunet/internap is probably very high on the quality side. but very spendy as well.
i'd put verio as a medium quality. maybe medium-to-high.