Battleships might be more efficient in terms of firepower per fleet cap, and even more so in utility thanks to being able to load them with the long ranged weaponry and XL slot weapons which gives you the ranged alpha strike to cripple fleets before they even properly engage you. And yeah, the corvettes are by far the most mineral efficient. Not 100% sure which class you are referring to as 'ship of the line' either cruisers or battleships. I realise it's not too helpful to say 'Hey it'll be so much better this time next year!', but I don't intend to undermine the experience before these changes were made, I played and enjoyed it a lot back then. See here for the patch notes for Stellaris 2.0 that contained many of the combat changes to come. So there are already solutions to most of the biggest problems with fleets and combat that exist in the console's current version. All of warfare and combat is massively overhauled (all for the better - oh so much so) in the coming patches and expansions. But really, that pattern hasn't changed much for me as the game has changed. Occasionally they'll happen in the other order depending on circumstances. My second fleet is often either entirely corvettes for a rapid response skirmisher fleet, to run around scooping up low priority targets while the main fleet deals with the enemies, and then a fleet of pure battleships for extra punch in the main battles.

Honestly, I've never cared too much about min-maxing, so usually my first fleet is mixed composition of the different classes as I unlock and can afford them. Also if I remember right, I think you could put the fleet wide bonus modules onto battleships back then, they can be handy too.

Click to expand.Not 100% sure which class you are referring to as 'ship of the line' either cruisers or battleships.

How to play stellaris military wise