IMO both of them quite fun to play, its depend on your tea cup.

If you wanna start to play DD, USN is the better choice - better concealment and fire range. Clemson & Nicholas quite fun to play , especially on low and mid tier battle - both of them have very good concealment (put camo on the ship for more better ninja, its worth).
Tier 4 captain skill is quite enough to play this DD line (put secondary advance fire training for extra range, so you can shoot in ninja vanish mode when inside the smoke).
Remember to move along the island for extra concealment, don't put urself in open water unless u have another DD as ur backup.
Normally DD player is the one who help ur team to "GROW BALLS" to his team - yeah most all of time DD player will die in the game so its normal, so learn how to use WASD hack, speed, and predict the enemy torpedoes come from enemy DD. Remember to drive ur DD like drifting racing car. I mean it.
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As for CV, you can pick both of the line (IJN or USN). Playing CV is quite a bit complex since it have variety type on it - rather you wanna pick air dogfight mode squadron - means more fighter plane; or bomber carrier squadron - means you have more torps and bomber plane.

I'm play both of them, but if you want extra plane to dogfight & plane endurance, go get urself USN line.
IJN line has better concealment and service time - due the IJN CV carries less plane compare USN CV.

For starter, train while farming ur captain until it reach tier 3 captain skill. Just pick plane service and side arm for ur plane in captain skill. Try use manual drop on torps plane and learn how to use timing when u want to release the torps, expecially when you targeting DD ships, since their move fast.
Remember not to release the torps to close to enemy when targeting ships or ur torps - if you play cruiser or DD you will understand why ur torps ain't hit even u too close to the enemy ships (If you want understand what I'm telling you, better you find it urself).
As for bomber, you can use auto drop for it, just make sure you adjust the target (the oval look area drop) before the plane want to drop their bomb. USN CV line has better bomber squadron since the target drop more smaller, which is better.
Last but not lease, don't be static and keep ur cv moving.

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Sorry for TL;DR. Conclusion - its ur choice. 
Too be honest I'm enjoying play all type of ships in the game (from cruiser ---> battleships ---> Destroyer ---> Aircraft Carrier).
Took me 3 month to understanding the mechanic of the game. I'm also like you, been taste defeat everytime when playing - I'm just got 15% win rate in battle back then. So I'm focus on Co-Op battle and train my aim and skill; at the same time farm as much exp and credit I can. Right now I'm feel happy with my achievement although it took me some time recover it back.
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My profile detail.
https://asia.warships.today/player/2012487869/ArchKongou

HE spammers? Mehhh.. More like this. Heh.

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Anyway, its feel good to keep pressing my left mouse button.