>>721086478
I don't know what you mean about some of those ships.
Zoltan ships are pretty great, Zoltan B's dual Ions are technically enough to take down any other ship in the game and the Pike Beam deals a ton of damage and pulls crew away from rooms to repair a ton of subsystems. It basically just needs an additional Ion of some sort, anything from another Ion Blast 1 to a Charge Ion will set it for the rest of the game. The other Zoltan ships are similar, and the Zoltan Shield gives you such a huge advantage in the early sectors you can completely skimp on defenses.
Engi is the same except you have to be careful on your drone usage. You have all the Ions you need to completely strip a ship's shields from the start, just autofire the ion into shields, turn on your combat drone, and let it do its thing. Get a defense drone or cloaking to beef up your defense.
The Fed Cruisers' Artillery isn't super great, but it is a shield piercing weapon that you start with. Back it up with a small bomb or missile to shut down enemy offenses while it charges and let it work. Fed C's flak artillery is deceptively useful because it's nearly guaranteed to take down shields every time it fires, enabling you to follow up with more basic weapons to destroy whatever subsystem you want. The shots also cluster really well and virtually never miss rooms. And the ship has extremely strong boarding early on, so you get extra scrap for killing ships that way.
Rock A's missiles do kind of suck, but the ship is great for either branching out into a traditional weapon setup or getting a teleporter. Stealth B is arguably the worst ship in the game though just because of how likely it is to take a weapon hit early on and enter a death spiral, the amount of scrap you need just to make it reliable would be enough to set you for multiple sectors on other ships and it will still struggle past sector 3 without help.