Guys, it's pretty silly to try and make up a perfect fleet roster. You're making the assumption that you 1) need a certain fleet mix (but you can't make that assumption until you SEE what the enemy has) and 2) that there is a perfect fleet.
Instead try to understand what each ship is good at and build accordingly, with an eye to what your enemy is building.
Here are some rules of thumb:
a) LRMs are your early-mid game workhorse unit. They're primary advantage is their cheap cost and extended range.

Kodiaks are your mid-late game workhorse unit. These guys take a beating and dish it out. They just get better and better as they game goes on. Importantly, small squadrons of Kodiaks can "tank" larger enemy fleets and can often solo well defended worlds.
c) Flak should only be built if the enemy builds carriers. Sure, they are tough, but they are a weak fighter and almost useless against enemy structures. Better to invest in labs and tech up to Kodiaks.
d) Hoshikos are useful late game. They will rarely turn the tide in battle, but they will make your fleet just a bit tougher. Not a priority. Maybe a 20th of the fleet.
e) Cielo's are an excellent support unit -- you'll need only a handful of these to get all their benefits. Maybe a 10th of the fleet.
f) Cobalts -- these are GREAT for leaving laying around your worlds as a reserve against a siege ship attack. Otherwise... I mean, they CAN be useful if you upgrade their special ability. In most games you'll need to built maybe a grand total of six of these and then only to help your first cap clear worlds.
As for capitals, Dreadnought, Dreadnought, Akkan. If you're in a game where you end up building more caps than three, either you're doing something wrong (you're better off with more ships of the line) or you're screwing around.