Rulebook arrived, and the quick skim through I've had seems to have sealed the deal in favour of the UCM and PHR fleets.
Roll on payday and I'll order starter fleets for both, it's good to have a plan
FWIW, I find the UCM fleets strengths to be:
1) Access to excellent firing arcs, making it easier to use "No Turn" special orders while still shooting effectively.
2) Many options for spiking enemy ships, from the obvious Lima support frigate and numerous Flash superlaser ships to the less-apparent Jakarta escort frigate (which are cheap, lose very little for Active Scanning, and can operate as single-ship groups, which is unusual for frigates).
3) Above average saves across the fleet.
4) Strong Burn-Through weapons on multiple platforms down to light cruisers, giving them a fairly reliable armor penetration capability when needed.
Weaknesses would be:
1) Below average speeds.
2) Battleships lack a truly strong single weapon for reliable ship-killing on orders other than Weapons Free.
The PHR strengths are:
1) Top-tier durability, with both strong armor saves and extra hull strength across the fleet.
2) Access to Burn-Through and Flash weapons all the way down to the frigate category. Supernova lasers are weaker than the UCM versions (unless paired) but they're available on even more numerous ship classes.
3) Above average Scan ratings, extending their ranges and making close actions safer for them.
4) Battleships have Crippling weapons (and see above for the point about Scan ratings helping with using those neutron missiles on the Minos).
5) Top-tier bombers and loads of carrier options. Toss-up as to whether the Scourge or PHR bombers are the best in the game, but it's certainly one of the two.
Weaknesses:
1) Slow, which is more problematic with them than the UCM since you want to get both those side arcs bearing on foes.
2) Broadside armament is harder to get mileage out of than forward guns are, although even a turn or two on Weapons Free with all guns firing can make up for a lot.
3) Troopships are expensive, as are all their frigate hulls. Probably worth the cost, but you will tend to be outnumbered or outweighed.