Taran beat me to it, I'd take a poseidon for sure, and use its fleet carrier traits where possible to give you a couple of extra flights per turn. You might not think this sounds like much, but you can use it to re-stock some of your other ships that carry fighters. And considering you can use fighters as an interceptor; your away laughing.
I'd then consider a couple of apollo, and either an omega or a marathon, to form a core to the fleet. Out of my experience in the campaigns we play in our club, you do also need a good mix of skirmish and raid level ships, like hiff said.
I'd spend an entire battle point on hermes, coz they are a pain in the backside, and probably another point on two deplhi, and a third on 4 chronos. Or take 4 hyperion assault cruisers. Okay they lack the heavy firepower of the normal hyperion, but they are skirmish choices, and, aside from the tantalus, they are the only ship in the fleet geared towards a planetary assault in the sense of troops and shuttles.
My fleet would consist probably of:
1 poseidon
2 apollo
2 marathon
2 deplhi
4 Chronos
4 Hyperion assault
8 Hermes