[2019] Okay, what is better to get! Dallas or Pensacola?

My favorite is Pensacola, since she's much more unique than dallas - Dallas is a fine ship, but there are several T6 6-inch cruiser who all play kinda similarly - you get your IFHE out, keep distance and do insane numbers of damage. Even though Dallas is the only one who has an entire line of ships similar to him.
While Pensacola is more about high-risk - high reward playstyle. If you find Omaha's squisheness manageable - you may do well in Penscola.

Best of all, of course, would be both. But be prepared that if you go to higher tiers - CA's are actually more tough ships, while Seattle and Worcester feel better when positioned behind the islands.