I understand some people like to have an entire debate, but honestly, there is only a ramp up grind, nothing more, and it's pretty easy to speedrun the game under 50 minutes.
Vitality: 5-10-15-20 are the breakpoints per level where you don't get one shot anymore, outside of a crit (which you won't survive anyways without grinding double those points or triple). So simply get enough HP to at least not get double tapped and call it a day (last boss cannot one shot you at 20).
Dexterity: Kinda useless stat, usually indie games forget how OP attack speed can be (attack speed are double value of their damage counter parts), but in this game it's the opposite. Whatever unit speed they're using, it's literally 1 Dex = 1 Attack Speed, so not even percentage.
Even if you attack like a machine gun, you'll never out damage the enemy before they hit you during their recharge time, and you'll need A LOT of Dex to even reach those breakpoints (test it on the wolves and see what I mean in terms damage vs. attack speed value points).
Also, because you need items with decent levels in them to get the pay off, you may as well not put any points in Dex all (explained later).
Strength: Exponential increase of damage, I couple of points take you from 5 damage to 30 average at the start, and you're already one shotting enemies at he start. At around 70-80 damage, you can do quick runs in the first level without breaking a sweat.
Potions: Completely useless, they take a turn and barely heal, couple with Dexterity and it's inflated cost to pay off, you're just wasting a turn for no reason.
Milk: Early upgrade is worth it if you plan on doing body runs (simply quick grinds) so you have a high chance of finding the Roulette (it's worth for the early 50 coins alone), otherwise can skip it if you don't want deal with RNG.
As for the Charms (I didn't get all of them so based upon my drops so):
Midas Charm: Very strong early game item, since you should focusing on gold rather then XP (everything in this game is gold driven), and makes the first level give on average the same amount of gold as level 2. Only item that is even worth it with Dexterity early, and only for specific people (the ones who want to stand around punching a slime for 30 seonds).
Vampire: No matter how you run the math, it's the only one that scales both early and late game. 6-24 Heal early on vs. 5-10 Block on average for the Shield is a no brainier, and late game, when you're doing 800-2500 damage, while bosses are doing 300 tops, that's also not a debate (plus it sustains you against Counters and XP farming if you want). Benefits massively from Strength.
Slow: Early on can remove 10-25% of enemies Recharge, and it more reliable than the Stun, potentially letting you kill an enemy before they even get a turn off. Haven't found any other better early game items so far, especially from the first level. Only item that benefits from Dexterity, but only if you can actually lock them down, otherwise go with Strenght.
STR Shift: Low-Key the strongest and best QOL item in the game, removes a large chunk of the grind (you only need to focus on strength technically) and scales really well with a level or 2. If you use the VIT breakpoints above, you're pretty much set. Only issue is it can be a pain to get since it seems to drop from the second area.
Technique: BIS Power Charm, 1 or 2 levels make it so every other turn you're power attacking, and turns a lot of problem enemies in 1 shots. Scales massively with Strength.
Power: Extra 12%+ damage everytime you hit and not get hit. If you're not one shotting enemies and such, you're bascally Slowing them forever while constantly hitting them, meaning this charm has infinite damage. The only time a Dexterity build can work, but since you already are using STR Shift, that pays off by itself.
The only other thing I can say is that both Training and Charm Slots are the most cost efficient things, there is not point in buying a Stat by itself for 200 each and more Charms is better than getting an extra reroll on your charms.