oh wow, a question I can answer since I have this job!!! :D I also expect Yarr to list his opinions as well since he has acquired a few kingly items of his own.

Weapon slot: fully upgraded relic (haha funny, mjollnir lol haha) or asklepios(actually attainable) : Kraken Club if u are in a LS lucky enough to own one of these ^^ (mistiltein is highly overrated, and purgatory mace bleh)
Note: Dark or Pluto for resting....duhhhhh!!!!
:idea: However the hierarch belt and the errant/mahatma houppelande may replace this staff altogether with the asklepios and the astral aspis, because there is 60 MP you will never gain if u rest with the dark staff :!: So IMHO, this is why the healing staff has got to be the dumbest bought staff on the server because you are spending 2 million on 50 MP you will never see because you have to switch staffs to rest!!!!!

Off weapon slot: astral aspis or genbu's shield

Marge Shield: yea....funny

fazasher death weapon!!!!!

Ranged slot: Hedgehog Bomb (ENM item, it's in ammo, look it up, its nice

)

Head slot: Trump Crown (I now own it, GL getting 1 : P) I reported about it here:
http://ffxi.allakhazam.com/db/item.html?fitem=8900
no gay condom hat yay! runner up is fairie hairpin! - screw zenith blech, noble's = No Thnx

Neck Slot: I have seen a few ppl using all sorts of things (torques etc.) in this slot, however I found a great item but it is rare/ex and requires Rank 8 fame in Bastok: The Republican Gold Medal!!!! Read up

Earrings: well here is where that HP/MP detriment comes in my choice in these 2 slots is 2 astral earrings but atm I'm not sure if I'll ever even own 1

Body slot: Cleric's Briault (I like this better on whm than the dalmatica for 3 reasons: the regen potency, the +24 MP at no HP cost and the - enmity, of course the 2nd best choice I feel is the Noble's because as a whm, your cure potency is more important than stats found on a dalmatica. :!:
However dalmatica is great for other magic jobs, you lose 3 def with the Whm AF2 but the reasons listed above is why I like it better than dalmatica, we'll lose HP/MP later in the earring/ring slots :D
Note: errant/mahatma houppelande is also a necessary item to have around for those "OMFG I need to actually rest because my refresh is too slow moments."

Hand Slot: Cleric's Mitts *better IMO than the zenith because where as zenith offers a mere magic attk bonus with MP+/Hp- (which no whm really needs as much as making his enfeebs stick on those God mobs) the enfeebling bonus of the AF2 plus the +MP with no deduction to HP and -enmity is a realllll nice touch.
The 2nd choice is the blessed mitts for the enmity and haste on it
3rd is zenith
&.......SE can shove the noble Mitts up their rear (these suck :!: )

Ring slot: Vivian Ring (rare/ex "Hey I have friends and they let me have this ring!!!") this ring is really a +1 of the serket, not only does it add 50MP/-50HP but it also gives you +1Int and +1 Mnd!!! badass :D
The other slot: Shadow Ring - yea....ok......mmmmhmmmmm.....dream on!!!! However, Yarr buddy you may get your hands on one of these at the rate you guys are learning and squashing Dynamis
Ok, back to reality:
More MP: go with Serket Ring *yawns*
More Mnd: Pluto Ring (dark Ring+1) or the aqua ring (runner up)

Back Slot: Errant cape: dream on kiddo
The +1 errant cape: The Mahatma Cape - I have seen this bazzaared 1 time in my whole playing career and it was about 25 million however the fact that I even saw it I felt lucky because I never even knew one existed on Ifrit, to learn what a pain in the ass this cape is to craft read up on it.
Note: I didn't list the shadow mantle because it's seriously a Pld item onry!

Waist Slot: Hierarch belt (I have yet to hear of or find a better item, I am curious if their even is 1

: )

Legs slot: Cleric's Pantaloons. The zenith slacks don't hold a candle to these, The healing Magic +15 makes these supreme whm pants! my runner up would be the JSE blessed Trousers which I also like better than zenith in this slot on a whm.

Shoe Slot: AF2 again, Cleric's Duckbills wins!
runner up: lvl 70 blessed pumps JSE
zenith

: explain why a whm would need Int+2 and Chr+2 in comparison to the other items listed above

: yea, thought so.
:arrow: other cool but uneccessary whm items or items for all jobs in general:
opo-opo crown
goldsmithing sunglasses or crafitng items (chef hat etc.etc.)
Well there you have it, my opinion on what I think is truly the best of the best for this job, as well as what I myself am building towards.