Jervis is a perfect hybrid for her tier with some tools to help her job, like long range sonar and short smoke screen that can save you many times, adding 10 torpedoes single launch and a good DPM to fight almost every DD that contest your cap, and finally you can use stand or fall, which is a strong skill , all this stuff means it's better than the premiums too, except Cossack that has a little bit more DPM but less torps, but for Cossack you have to pay 12500 doblouns, for Jervis instead 9000000 credits