Caldari Frigate/Cruiser Information

The Merlin is a good guns-and-missiles ship, and it's very customizable (you can put rail guns on it for long range, or blasters for short, and similarly standard missiles for long range or rockets for short).

The Kestrel is an all-missiles ship, but because it also has decent cargo space, it can also be a salvage ship, small cargo hauler, etc.

Going to cruisers, for Caldari, you have the following:

Osprey = mining ship, it has bonuses to mining, also big cargo, so could be a transport too.

Caracal = all missiles, shield tanking, good for missions; you can mix and match standard missiles, heavy missiles, and also have 2 drones for emergency here and there.

Blackbird = Electronic Warfare platform, for jammers, scramblers, etc. Although it can mount weapons, it's more of a PVP EW ship.

Moa = combat cruiser, designed to be used with rail guns at long range (80KM+). Because long range rails track poorly at close range, and because most NPC pirates rush you, the Moa is more suited for sniping / long-range PVP than for missions.