Australia liveaboard- ribbon reefs/cod hole vs. Cairns reefs advice needed

[purcitron]

i plan to do a 2 or 3 night liveaboard in August.

i would greatly appreciate suggestions for which liveaboard to chose based on dive sites.

my options are:
1. "mike ball's" Spoil Sport to cod hole & ribbon reefs
or
trips closer to cairns:

2. Scubapro to Pellowe Reef, Flynn Reef, Milln Reef, Moore Reef and Thetford Reef
3. Ocean Quest to Norman Reef, Hasting Reef, Saxon Reef
4. Kangaroo Explorer to Moore, Milne, Briggs, Elford and Thetford reefs

experience & advice would be most welcomed!
i'd like to contrast the northern reefs (ribbon reef, etc.) with the cairns-area reefs please.