Ok I can only really comment on the ones I've seen so far mate (these are personal opinions so I couldn't care less what flames i get 
)
Toxic Tarrantula - hefty damage, not hugely fast or bright, but can really take aggro
Spiderlings - they suck, end of (however funny they may be)
Fortunata Seer - above average damage, but has very good range and a nice perception increase, but lacks anything tasty (although she is resistent)
Forunata Mistress - loads of damage, quick and has a lot of fun secondary effects to throw in
Night Widow - its a night widow, nuff said
The Mu Pets - generally i think they suck as they get so much aggro and pull groups long before you or the team are ready (BUT the dom pet does spam a heal fairly well)
I am yet to see enough of the Mako pets to know really. And thats my ideas so far. ALthough 'screamer has the seer and it works bloody well with him i must say. And when sound gets his Arachnobot Disruptor I will have more of an opinion (just 7 levels to go lol).
The Mu Guardian (dominator) is really useful. He has a good heal, forget about damage.
I really should do something about this signature.
I want an olympus titan.. now that wud truly be an epic pet or a quarry.. is it just me or is the naming convention of "epic" a bit over rated for the patron pets..
I want the ghost ship as a Patron pet. Invulnerable to all damage and spawns dozens of ghosts to fight for you. Now that would be epic. Imagine the PvP! 
Ok so how are the epic pets? whats their damage and accuracy like? forget the downtime of them.
I just wonderd if anyone knows what their base damage is and if they help out or not?
Thanks