UA can't be traded but the ammo from ingame trade terminals (TT) have the same value. 10 ped ($1) buys 100k ammo, the starting guns use 50-100 ammo but later guns use hundreds, then thousands of cells per shot, so you can't tell the ammo cost without knowing what gun one uses. The only advantage of UA is that it can be used for almost all kinds of weapons AND for mining, but it's a subjective advantage as any ammo is freely available at TTs for fixed price. UA ammo is good for people who like to precisely track their returns, as looted ammo doesn't mix with UA, and if you plan to do, say, a 100 ped ammo run - you do exactly that.
To summarize: the Gold is the smallest pack that has armor with 8% running buff and the ZX sinkidus laser amp, which you can't acquire in game. The Platinum has more stuff but doesn't offer anything unique over Gold, nothing you couldn't buy ingame. If not Gold+, then you are better off depositing raw peds and buying stuff in game.
If skills pills are what interests you, the Starters Pack Refill offers more steady supply than starters packs, let alone the strongboxes. But, frankly, skill pills are a waste for a beginner. A progress of a newbie is blazing fast as it is, you gain levels by days, not by months. Since skillgain depends on amount of peds cycled, a skill pill gives a tremendously greater bang for a buck much later in game, when you cycle in a hour (that a pill lasts) more than you currently cycle in a week.
BUT, in the end all depends on how you are going to play. If you consider a starters pack a big investment then of course you need to nit-pick. Low budget players value that amp because it serves them for months and years on low level mobs. But if you plan to shove in money and progress fast, then you indeed will outgrow all the gems of the packs in a blink, as Aio stated. If you see yourself depositing $50+ a month early, you can either safely skip the packs altogether or consider a gold/platinum pack your first month's supply, even if you won't have a use for its items a month later.