I think we should try to hammer out what exactly the ship ought to be used for, that'll let us inform our design decisions. Whatever we do, we want it optimized to hell.
If we go for Arrowhead, that's 'very killy in fore and sides' and 'more engine, more zoom', along with cargo and docking. The price is easy fore torps and utility hull space. Now, I think the latter two could be mitigated with a secondary hull, but that is not guaranteed and might cut into the 'zoom' bit.
This would serve well as the head of a fast-response or attack fleet, drop out of warp and start blasting the hell out of fools. If the plan is 'speedrun their shipyards', this is the boat we'd likely do it with. Disadvantages are the vulnerability to ambush, so you'll need to give it escorts in its softer arcs.
The saucer feels much more 'line of battle', or 'fleet anchor'. It's the only one you'd be able to send out alone, not that that's ever smart to do with a warship, but eh. You could plop it down in the middle of a fleet and it'd basically do everything a normal ship does, but bigger.
This is the generic general-purpose option for doing all of the war things pretty okay. Use it as the core of a fleet, but it's not going to warrant any special tactics or provide any particular advantages other than just being big.
Now the half-saucer intrigues me. Presumably we'll be able to fit torps and go heavier on the engines, basically do everything the other two ships do but a little worse. It's the compromise pick, but that may not be such a bad thing. If we go for half-saucer, we're essentially going full Manta Ray, which I know some folks will enjoy.
Folks, I must be honest - my heart is crying out to me for arrowhead. But half-saucer is a good alternative.