Ships are highly varied and have many strengths and weaknesses. Having torpedos is a strength, but often don't work well close in. I like Nova canons, but others hate their inconsistency. Battleships are definitely tough, but can be overwhelmed without smaller craft to defend. If you are just starting, I would go for a balanced fleet with a little bit of everything. I have files for paper Imperial, Eldar, & Chaos that can be for cheap fleets.