Well, it is difficult to say so.
Regarding the DDs, of course DDX seems to be the best one, but Guering is not too
bad, especially because with the remodeling it can to use two torp launchers of 5
tubes.
The best CL, from me is the Janeu II, of course Brooks is good but you need that
your gunners have more level for use it propperly.
The best CA, probably Baltimore, but the next ship wiil be the Alaska, so the
Northampton is not a bad ship, especially if you use on it 3x8" 55R.
The best BB, Sebastopol is good, but whichever you want above the Lvl 70.
CVs, all of them unless the Bogue.
Regards, Amargar

Look above for Blazin_Spam ^^^

So far:

DD: Somers or DDX (Somers is fun with torps but DDX is just fun all around)
CL: Brooklyn (Loved it so much I played through Cleveland and Baltimore)
CA: Pensacola (Got it from the event, couldn't have made a better decision)
BB1: New York (ATM, since it is my only Battleship)
BB2: Hopefully Colorado (Just need one more level)
Past that?: Ummm, I'm not there yet.

I suggest going to:
http://www.trainworld.us/NF2/English/Ships.html

And clicking on the nations at the right to look at their ship lines, gives you an idea of
what is for the taking.

Useless post noob

CL for me is definately atlanta

cleveland is like the downgraded version of baltimore

but it really depends on your playing type

long range guns go for portland
fast manuever go for baltimore

DD: DDX
CL: Cleveland
CA: Baltimore
BB: you're choice
CV: CV5