Healing, summoning spiritual weaponry/guardians (up to and including Planar Ally / Gate spells), buffs like Guiding Bolt / Bless / Guidance. So much Guidance. I'm also a huge fan of things like Augury, but that's GM dependant. If we talk about the cleric without the domains peeking in, those are going to be your staples.
* Arcane... is tricky. I mean, being able to banish with a Turn Unead channel is pretty awesome, but very game dependant. As is Spell Breaker. If you're constantly being cursed in combat, it can be handy to have, but very game dependant. Good as a counter-magic specialist, I suppose. Arguably better than Abujurer at being an anti-magic specialist but Improved Abjuration gives it a run for its money. Without magic to contend with, however, it falls back on those spells mentioned above, or a discount blaster. I honestly suggest Knowledge over Arcane - much more versatile.
* Death is fun. Necromantic energy specialist, either by hitting with a blade or going spells. Dex-focused, so it ends up being kind of assassin-y, which is fun to play up. At least I had fun. In theory, you can do the whole undead army thing, but I think that you should save that for Oathbreaker and Necromancer, and stick with being "necrotic energy master." You can easily bounce between spells and melee with this, making it a rather fun necro-gish type.
* Knowledge. A solid diviner class. Can be really good, depending on the game. Between the class features and Guidance, you're probably the best at skill checks in the game for along time, and Read Thoughts is nothing to sneer at in the social department. Not great at combat, but pretty awesome at everything else. Arcane eye and scrying for exploration abities.
* Life. King of healers, and a forte of clerics as a whole. Can't go wrong with this.
* Light. Bleh. Discount Evoker. While it may be good at radiant spells, the cleric really doesn't have enough spells to really be a good blaster. You end up defaulting to spamming fireball and Sacred Flame. You're not very good at the thing you're supposed to be good at. I suppose that's the price of trying to be a blaster in a class not meant to blast, but its just trying too hard to be a sorcerer or wizard.
* Much like above, Nature's spell list wants you to play a discount druid. You're not even getting Entangle, though, which makes me sad. Charming animals with your Channel Divinity is nice, but just saves a spell slot that druids would use for a spell for anyways. That said? This particular class is built to use Shillelagh with elemental strikes, and dampen elements, making this a great class if you expect to deal with elemental problems at some point. Not much use otherwise, though, especially since most games take their time getting to level 8, and don't last for much longer after.
* Tempest. Basically a lot like Death, but with lightning instead of necrotic energy. It has some great utility and damage mix, and which ends up in some good battlefield control as well as potentially very good nova damage. Its just plain -fun- to mess around with.
* Trickery is trying to be a Rogue, much as we have light-sorcerer and nature-druid types. Get a tentacle rod, do some sneay things, poison people. Can be good if you have a stealth-focused group and want a cleric in the mix.
* War domain. Remember those spirit weapon spells I talked about above? Just like the Life specializes in healing, War specializes in those spells to do lots of damage while wading into combat personally. Life buffs / heals, War melee's it out.
Life, War and Knowedge basically cover the three big points of what I consider cleric's specialties as a whole. Healing/buffing, buffed combat, and divine divinations. Those are pretty much the cliche cleric. Everything else, in my opinion, is the cleric trying to be something else. Someimtes that something else is fun to play, but not always that great at it.
