Magicka vs Health vs Stamina

[DorostheConqueror]

Health is 100% useless as long as the health-regen exists.

[The Dog Whisperer]

Except you can't survive any hit with 1 health whilst you can perform any power attack with 1 stamina.
I was doing 1:3:1 on M:H:S but since I got the Nightingale Blade all I need the Stamina for is rolling and holding my breath. :\
I'm pretty sure you can adjust the power of enchantments on weapons? So [assuming you're using enchanting] put "Absorb 1 Stamina" on a weapon and then you've got infinite power attacks.
If you find power attacks important, for some reason. Only really seem to use them for sneak kills.
Haven't yet used a build that doesn't include some form of magic, so I could say (In my completely biased opinion) that Magicka is the most important.

Although re the OP; On every character my first upgrade has always been health.
You can argue that Health regenerates, but using that argument against investing in it means you have to heavily rely on Restoration.
And even with that, there's only so much a base of 100 Health is going to do for you.
I have 290 Health on my current character, and a Frost Dragon can kill me with that obnoxious animation where it picks me up and thrashes me around from ~60%.

[Talamare]

Health is 100% useless as long as the health-regen exists.

Except you know... it isnt

since you know... you can get 1 shotted, then wont be able to pot in between

[MaKo]

For my melee fighter, I first preferred Health, until I observed lack of Stamina. After that, I took Stamina, but eventually I observed that I have it enough for my playing style, and after that - and especially during 1.2 patch - I have preferred Health. For warriors, it is the raw power (Health) that matters, it makes you swinging your sword longer. EDIT: By gears, I have lowered the magicka cost, so that I am able to summon some decoys/aid for battles.

[deadknight]

I always go for health first.....then stamina if i play stealth/warrior or magicka for mage