As a dedicated Premium player, I've weighed all these and more. And here's what I've found...
I 100% recommend the Shared Bank first, and as a high priority over anything/everything else you might be looking at, including more packs beyond those 3. Move BtA items around, stash stuff while TR'ing, all good. As of recently, you get 30 slots w/ the basic - that's enough to start (or more - 20 sufficed a long time). Any class/race/trees/extras are cramped if you are stuck w/ useless (but valued) BtA items on your main, or end up w/ some BtA gem on an alt that you want on your main.
Character slots - If you get the Shadowfell Conspiracy expansion (and I recommend you do, a great value, espeically when on Sale), that makes you Premium, so you'll have +1-3 character slots on top of a Premium's 5 slots - that's 6-8, which should be ample, at least to for early on (and compared to a Free Account's 3 slots!). Again, "more" is up to the player (
some have 40+ - whatever works for you!).
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https://ddowiki.com/page/Account_comparisons
As for the others...
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Shared Crafting Storage - I don't do much crafting, but hate to throw stuff away. Might need it.
Learn to throw stuff away or learn what to sell (Rare ingreds, only useful for UNbound crafting. Usually bring a good price on AH.)
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Shared Platinum Space (of course you can just mail it)
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Character Bank Slot
Once you have your main, sure. But only if they "need" to hold a bunch of BtC stuff - don't confuse this w/ stuff an alt-account mule could hold.
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Classes that look interesting and won't be on sale for a while, eg Tiefling Scoundrel (just came out in summer).
You do a lot of Iconic reincarnation, or plan to?
Myself, I focused on "more adventure packs" first, on the theory that "more packs = more favor = more DP" - and that investment pays for itself. I've been happy with that approach, and now (usually) have 1000's of DP in the bank and can use that to grab whatever random race now comes on Deep Sale if/when I want it. The same would not be true grabbing an Iconic early on and making more DP with that.
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Crafting Success Boosters?
First, you just said you don't craft.
But beyond that, with a Shared Bank, you can roll up a new alt and run them thru the Crafting Tutorial and grab 5 boosters for 10 minutes of effort, done.
Have you met the internet?