As far as I've seen and heard, many who fly Phantoms give them the "Fire-Control System" Upgrade. And I can see why. A Target Lock ability on a ship that cannot innately Target-Lock is huge.

However, unless I am wrong, you can only maintain one TL at a time (exception is the Weapons Engineer Crew Upgrade). This means that you are very likely to move the Phantom into a position that would enable you to shoot the same target on the next round. Which makes the Phantom predictable. One of the Phantom's greatest advantages lies in its unpredictability. Also, this is not a ship that should stay in the thick of battle for consecutive rounds (speaking from first-hand experience)

Ships with low health will be better off disengaging the current target (unless the benefits of staying on target outweigh the risks) and engaging a new one. And what good would a TL placed on Ship X do if you are moving to attack Ship Y? I understand that you can move away from the battle and return to attack the same ship later, but I think that the Phantom can benefit from another Upgrade at the same cost, the Tactician Crew Upgrade.

Tactician limits your opponent's movements for the next round. FCS gives opportunity for future engagements with a specific target while Tactician gives an immediate hinderance to your opponent's strategy. This leaves the Phantom free to either vanish from the battle to re-appear at a later time or disengage and move to another target, ready to attack and stress that one also. Yes, having a TL on a ship does not mean you have to go after it but you'll have a better chance of damaging it. Therefore, you would be more likely to do so.

Fire-Control Systems is great on a Phantom but Tactician serves as a better choice. What are your thoughts?

The issue is that a lot of us successful players layer the phantom with Rebel Captive so that the crew slot is taken. Tactician does fill a useful gap if you are only spending 2 points on it.

Ok, then that would definitely make more sense. Whenever I heard of Phantoms with FCS, I don't recall them being outfitted with Rebel Captive. Which led me to believe that Tactician would be the better of the two. But yeah, if you have RC, that ability is basically taken care of.

The Tactician also requires you to stay at range 2 while sometimes you'd want to stay further away or move in closer.

This might actually be fun:

Vessery, VI

2 x Shadow, FCS, SPA, Intelligence Agent

Another successful build involves using Whisper with a Gunner. You then spend your action on the Evade, knowing that you will have two attacks against the target, and the second attack will be target locked. It makes it very likely you'll hit, earning you a Focus token to spend during your defense.

Otherwise, it's not automatically bad to have a target you want to focus on. A damaged ship usually does as much as one at full health. Clearing that ship off the board can be as much of a defense as an arc dodge.

I think you've got it backwards; a phantom just shot at a ship and hit. Now it's got a target lock.

Do you really want to stick around and let it shoot you again?

I like the supposed predictability of the fcs.

Get a target lock on ship a, then you have options - be predictable for maximum damage against a ship you've already damaged, or switch targets to ship b, confident that your opponent will be sure that you're going after ship a again.

Do this second option, the target switch, once and the second time, stay with the ship you've got a tl on. Keeps your opponent guessing.