Despite its unpopularity, I went with Red anyway.
My experiences:
Difficulty: Jack Sparrow
Playstyle: FLY ME CLOSER, I WANT TO HIT THEM WITH MY SWORD!
1. Blood Axe: Amazing weapon, I've gotten 20-enemy-in-a-turn killstreaks before with it. If it's a living enemy, and you get a bloodaxe to it, it won't be anymore. Period. Doesn't matter how many HP it has, even a Hell Baron will insta-die to this, because if it has so many HP that you won't kill it in a single strike, the TU-refill effect means that you are attacking at negative cost, so the beefier the foe, the easier it actually is to get a kill frenzy off of. It's especially brutal to High End Demons and Mercs, both are high HP enemies that have very little value alive.
2. Vampire Sword: Makes the bearer nearly totally immune to damage. Not because of its effects, but because enemies will shoot at everyone else but that guy, so you'll have to toss the sword to whoever actually took damage. Guarantees a high level of uptime because you can heal damage taken even without needing an injury, just hit someone with it. Now, it SAYS it costs morale on use...
Red was second choice but I've read some advanced weapons come with attribute penalties/damage on use.
...but it doesn't, really. High Brave makes you basically immune to the morale damage, plus when you kill somebody you gain morale anyway, so the problem solves itself, as this is a lethal weapon.
3. Moloch Armor: Eh. On paper, it's nice. Has the TU-leech effect of the Axe, and counters the stun, which in theory, combos to make the two even better. The problem: -50 TU: The -20 on the armor combined with the loss of another 30 from not having Blitz. While the armor would be otherwise great, none of this matters if you cannot get to the battle. The low TU cap also limits how much you can tank up to make it to your next victim, since you can only refill TU up to your cap. Also, it can't fly, which further penalizes its already extremely poor mobility. With the massive movement penalties on this thing, you're lucky if a gal wearing this can make it out of the dropship before the battle is over. I finish an awful lot of fights on turn 1 or 2. By the time turn 3 rolls around, it's either straight up over, or all over but for the shouting.
4. Metallo: Can absorb an amazing amount of punishment in a fight with only a few days of hangar time, good drop capacity. Probably the second best flagship after Fortuna, but only because the Metallo cannot into space, as all are too slow to function as interceptors.
5. Scarab: Deadly Superiority Fighter, but too slow to intercept anything, since most everything that can actually fight has speeds in excess of 3K, which means any interceptor with a speed lower than that is pointless unless your target is willing to be baited into chasing you (has the circle).
6. Scorpion Dropship: Good synergy with a bloodaxe rush, but don't use it to ship anything but well-armored or shielded troops, or you will instantly die as enemies spawn right next to you, sometimes facing so, so you can't move without instantly dying and you can't not move without instantly dying either. Being able to immediately introduce your axe to someone's face, though, can mean the battle starts and then ends in the same kill frenzy. Otherwise, probably the weakest link of the package.
7. Destructor Suit: Surprisingly effective as a scout, but the actual weapon is not to my taste: Too high of a firing cost, doesn't produce the effects I want, since I already have cheaper, more efficient ways to cause mass destruction at range. I'm more of a precision-oriented player, I prefer to destroy things in a directed manner.
All in all, I'm not entirely sure what other Codexes would represent a trade up from this.