@oztea:
Cruiser + Destroyer = 2 shots, 2 hits, 5/6 combat power, Anti-sub, bombarment at 3
Battleship = 1 shot, 2 hits, 4/6 combat power, bombardment at 4
Both are 20 IPCs
Both are a good purchase
I disagree. The Cruiser+Destroyer purchase is a sub-optimal build specifically because of the inclusion of the Cruiser. This purchase only looks good on paper - in the actual game it is a poor purchase choice for a number of roles.
Want to get some combat dice into the water? 2 Destroyers is cheaper and, while you downgrade your dice a bit, the extra benefits that destoryers bring with them outweigh the loss of the 3/3 to a 2/2. Same goes for Subs - downgrade in dice, but they bring unique advatages that offest those crappier dice. For my plays, when my opponet purchases 2 subs it is a larger problem to deal with than 2 Crusiers.
Want to get some units in the water for a delaying tactic? Subs or destroyers are a cheaper way to do so (and, again, bring more benefits for their lesser cost). Same this goes for if you need to split your navy - what you want are DDs and SSs, not CAs.
Want to get a high kill ratio to beef up your navy? Buy a Battleship. You get an upgrade to the dice (2 4s is better than 2 3s, obviously). It costs the same as two cruisers, has at least as good a chance to survive (its upgrade at attk/def offests the 2 shot/turn advantage the cruisers have). In a straight up fight of one BB vs 2 CAs, the BB wins. Oh, and the BB has a batter bombard.
Need to go against sub-spam? Destroyers are the way to go, obviously. But because of the sub’s sneak attack, a Battleship is also better than 2 cruisers (someone can do the math, but the sub’s sneak attack means that something like 33% of the time a sub will only face 1 cruiser [on the attack] - and thus only face 1 roll of 3. Against a BB the sub is assured of facing 2 rolls of 4).
Have 20 bucks to spend and want a navy? Buy a BB or a couple DDs or SSs. They all fulfill their role better and do so cheaper (or at cost).