Shaman: Stamina vs. Wisdom

Compilation of Shaman STAMINA vs. WISDOM data points
(Note: This does not take +HP items into account)

• For each +1 to STA (below 255), a Shaman gains 0.05 hit points per level (so +2 HP per +1 STA at Level 40).
• For each +1 to STA (above 255), a Shaman gains 0.025 hit points per level (so +1 HP per +1 STA at Level 40).
• Given the HP-per-STA ratios +1 STA buys the Shaman an effective 0.025 (STA>255) to 0.05 (STA<255) HP per level

• For each +1 to WIS (below 200), a Shaman gains 0.2 Mana points per level (so +8 Mana per +1 WIS at Level 40).
• For each +1 to WIS (above 200), a Shaman gains ~0.0775 Mana points per level (so +3.1 Mana per +1 WIS at Level 40).
• Given the Mana-per-WIS ratios +1 WIS buys the Shaman an effective ~0.08 (WIS>200) to 0.2 (WIS<200) Mana per level

A Shaman can convert their own HP to Mana using various Cannibalize spells; the theoretical best conversion ratio being 1.60 (Cannibalize II @ Level 38) HP:Mana:

• Cannibalize I (LVL 24): consume 50 HP, gain 19-30 Mana (conversion ratio is 1.66 to 2.63 HP:Mana)
• Cannibalize II (LVL 38): consume 67 HP, gain 30-42 Mana (conversion ratio is 1.60 to 2.23 HP:Mana)
• Cannibalize III (LVL 54): consume 100 HP, gain 39-47 Mana (conversion ratio is 2.13 to 2.56 HP:Mana)
• Cannibalize IV (LVL 58): consume 148 HP, gain 81-82 Mana (conversion ratio is 1.80 to 1.83 HP:Mana)

A Shaman can convert Mana to HP using various Healing spells; the theoretical best high-bandwidth HP:Mana conversion ratio being 6.0 (Torpor):

• Greater Healing (LVL 29): consume 115 Mana, gain up to 350 HP (conversion ratio is 3.04 HP:Mana)
• Superior Healing (LVL 53): consume 185 Mana, gain 600 HP (conversion ratio is 3.24 HP:Mana)
• Chloroblast (LVL 55): consume 331 Mana, gain up to 994-1044 HP (conversion ratio is 3.0 to 3.15 HP:Mana)
• Torpor (LVL 60): consume 200 Mana, gain 1200 HP (conversion ratio is 6.0 HP:Mana)

Additional slow-rate high-efficiency conversion:

Regrowth (LVL 52): consume 300 Mana, slowly gain up to 4100 HP (limited-bandwidth conv. ratio of 22.78)

General thoughts:

Given that a Shaman can readily convert their HP to Mana and back, their HP & Manapools both contribute to their overall "Mana pool depth"
Given the HP:Mana conversion ratios we can generalize and say that 1 Mana Point > 1 Hit Point (in fact, 1 MP ~= 1.6 HP or worse).
Given our best-case sustainable HP-to-Mana conversion rate of 1.6:1, each +1 STA buys the Shaman an effective 0.016 (STA>255) to 0.031 (STA<255) Mana per level.

• For WIS < 200 and STA < 255, each +1 WIS buys the Shaman over 6x as much Mana (0.2 vs. 0.031) as would a +1 STA
• For WIS > 200 and STA > 255, each +1 WIS buys the Shaman over 3x as much Mana (0.08 vs. 0.025) as would a +1 STA
• Even for WIS > 200 and STA < 255, each +1 WIS buys the Shaman over 1.6x as much Mana (0.08 vs. 0.05) as would a +1 STA

For pure Mana consideration, a higher WIS *dramatically* beats out over a higher STA

That said, there are some meta-considerations as well to be taken into account:

• When you reach 0 Mana, you are OOM. When you reach 0 HP, you are dead. Therefore, HP are obviously important.
  
• The higher your HP, the bigger your "Cannibalize buffer" is, i.e. how much overhead you have to play with before feeling vulnerable.
  
• Since it's "easy" to reach your stat caps, any +WIS above cap is wasted and should instead be giving you +STA (and vice-versa).
  
• Draining your Mana pool is better than draining your HP, in that you regain Mana faster while medding than HP.
  
• Draining your HP pool is better than draining your Mana, in that others (esp. Druid, Cleric) can refill your HP for you much more easily than your Mana.
  
• None of this takes any special HP or Mana regeneration items into account.