Depends largely on what your playstyle is, though I'm kind of iffy about carriers because of their rather awkward playstyle at the moment. (Early tiers are heavily dependent on the finicky manual torpedo attack mode; divebombers are largely useless.)
Japanese DDs are a joy when they work if you like the torpedo ambush, but their lack of any useful guns and the general rise in player skill level with tiers makes them increasingly frustrating beyond Tier 6. American DDs after Tier 5 play radically different from general destroyer gameplay in their line below that and in the Japanese line, becoming tiny cruisers with the ability to alphaderp people who get too close with torps.
American cruisers are monster gun platforms but have a sharp playstyle break between Cleveland and Pensacola (Clevelands and below charge and overwhelm with rapid gunfire, Pensacolas snipe), with ships after Pensacola sliding back towards the Cleveland playstyle slowly as you advance. Japanese cruisers are generally weaker than their American counterparts but also have the torpedo alphaderp; the exception is Mogami, which plays like a giant Cleveland on speed.
Battleships stand off at range and should never accept close action, unless the only thing around is other battleships. Kawachi is okay but too-short-ranged, Myogi is suffering, Kongo is good, Fuso is amazing, Nagato is a bit of a downgrade in some respects and has to exploit its range to maximum effect against Fusos, Amagi is also amazing, Yamato is currently suffering from a bizarrely broken armor model that lets 6" guns knock its turrets out.