All dlcs are unique in a way and each has it’s own benefits. Generally they are a good deal and a mix of everything. Some of us got all of them.
The ships you get have been better before, the only really good ones now remain the Sai, Desert Eagle and Bear.
And you don’t really need the Desert Eagle, I myself much prefer the federation Wolf-M, but that is just me, and you will have to fly regular ships anyway, to progress to higher tiers, these are just helper ships and free sinergy/credit farmers.
It is, however, a great boost for new players, since with these ships you will earn more credits in games and get double free sinergy (which is small by default, but it’s really noticable difference if you fly premium ship or regular).
Say if you fly a regular ship you will get about 1000-2000 sinergy per game if you use several ships, with a premium I somehow get up to 2500, and if I use 3 premium ships in a battle I get up to 6500 free sinergy in a game.
Also, there are no repair costs on premium ships. I used to fly exclusively only premium ships with license in T2 and T3 for a long time, and easily saved milions of credits, ingame currency has never been an issure, really, so if you invest in this game early you will have a good economic future, but if you try to play for free it can get quite harsh.
In general, the DLCs are worth having and are a great boost in your midgame, they certainly help, but the premium ships are not the core of the game - except Sai, which is the best dlc ship and the best ship of it’s class in that tier.
Also, all pirate ships get unique pink trails that are really cool to look at.
It is a good idea getting the dlcs as soon as possible, and maybe more of them, because effect on the bonus loyalty and credit gain is not retroactive.
I would personally recommend getting 2 dlcs for start:
after that, I would recommend getting the second 50$ dlc.
The elite pilot and dead man’s chest are not really that much worth it. You won’t need the ships you get in those packages, the medium ones are considerably more useful, but the most important thing you will need is the GS.
After that, if you will need more GS, I suggest buying the biggest package you can afford through ingame store, since you get 50% more on your first purchase, at least I know that there was a promotion for it some time ago, not sure if still is.
Oh, the most imporant thing: Do not start flying the premium T2 and T3 ships you get right away! Do not even touch the T3 ships until you reach and play in tiers that are corresponding to the regular ships you already own, because you will get matched against experienced opponents with maxed out ships and premade teams that will stomp you, you will also lack the means to properly equip these ships. Leave your T2 and T3 premiums parked until you started flying with regular equivalents in pvp! But you will need the license and loyalty/credit/warehouse/loot boost as soon as possible to maximize your progress anyway, so it is good to get the dlcs at the start regardless.