depends depends depends, the armies you face should shape the way your army comes together...
if shooter army take the dragons with the falcon, both wraithlords, and the banshees, round it out with the farseer and warlocks for anything that is neglected
if a close combat army, take 2 squads 4 reapers, the farseer with fortune, and the warlocks with destructor. two squads of 20 guardians, and a farseer w/ guide (you should have a few points left over)
if an all around army use the one farseer and warlocks or wraithlord to soak up firepower, pour on the St4 shots with guide and all 50 guardians, and take the falcon and either banshees or dragons (whichever the situation calls for)