I was looking through the spell section in the Manual, and saw quite a few neat spells for Domains, like Executioner's Eyes for Oghma,Mask and Mass Domination for Bane...so, I figured I'd ask on the board,
Which is the best Cleric type in IWD2?
What would each domain be best used for?

Ilmater: Has many spells that help you fighting against evil opponents. Has also protection and buff spells.

Lathander: good deity choice for clerics, who want more offensive (fire-based) and healing spells. Getting improved turning for free helps also, when you are fighting against undead.

Helm: Many protection spells. Could be good choice for multiclass warrior-cleric.

Tempus: the best choice for cleric, who fights a lot and uses battleaxe.

Bane: if you like domination spells, this is for you.

Talos: has many offensive spells (both electricity-based and area spells), even more than clerics of Lathander, so take Talos, if you like clerics, that can cast many direct-damage spells

Oghma, Selune, Mask: they have many spells, but I don't have idea how to use them effectively.

I'd say Lathander for domain spells. Perhaps Ilmater has better domain powers and maybe even equally good spells - that is, if you prefer direct physical interaction to casting the blazing hell on your enemies.

I went for Lathander. My cleric didn't even have a single combat feat and he was still a good frontliner. In casting, he rocked. He had Greater Spell Penetration, Spirit of Flame and Greater Focus: Evocation. A bit like my two sorceresses :D

I'm playing a barbarian/battleguard of Tempus at the moment and he rocks. The axe feats work nicely and the domain has nice buffs, all excellent for fighter types.
For non-melee though i'd probably go for Lathandar: invaluable healing and raising spells.
I once tried a Sorcerer/Stormlord of Talos.......unstoppable. The guy couldn't be touched. Just left him in the back line and cast offensive spells like they were the new fashion.

Most domain really only work well if they are multi-classed properly however. For instance:

Barbarian/Battleguard of Tempus
Sorcerer/Stormlord of Talos
Rogue/Demarch of Mask
Paladin/Watcher of Helm
Bard/Lorekeeper of Oghma

Fighter works well with any domain (and class for that matter) but I find they work best with Lathandar and Illmater.

If there was a Malar domain a Ranger/Malar or Druid/Malar combo would rock! :D

Oh, well my first cleric was a Shield Dwarven Battleguard26/Fighter4... He was an ass-kicker. Two axes in hands, ambi + two weapon and 3 at martial weapon focus: Axe... What can I say? No stop, a tank... :)