I rarely design military ships until I have the Black Hole Weapons.
Too much micromanagement, too many new weapons techs being researched at a time, too much money wasted, etc.
I keep the galaxy at peace with eachother until I can design ships like that.
Yeah, it's weird, I know. I don't spam races into going to war with one another, I try to keep them at peace.
It is in my opinion more challenging, especially on Suicidal.
And are you like a NOOB or something Ralphander (just a curious question, I did put a little too much emphasis on the NOOB part, I know).
But if you like to waste your money to have (in a way) a more epic game (although there is nothing epic about the space battles in this game, except in DA maybe, I wouldn't know about TA, I don't have it), I would go for Phasors (Laser tree), Nano-Ripper (Mass Driver tree), and Quantam Torpedo (Missile tree). This is of course based on DA since I don't have TA (it also applies for DL). I might update this info based on the positions of these on the tech tree, cause I think I made a couple of mistakes in my judgement.
Eitherway, these weapons should keep you well armed against any threat (even the Dread Lords I'd assume, also assuming that you hit them first and have enough defenses to take at least 3 of their hits before you manage to destroy them.
Like I said, I'll correct myself later.
Till then...........
That's not an apple, that's a bomb.