Default Pantheons vs Custom Pantheons

Speaking of deities, I've been considering my setting's pantheon. At the moment, my homebrew setting's pantheon of deities is kind of a mess. Some base Greyhawk deities (Boccob, Corellon Larethian, Ehlonna, Heironeous, Hextor, Kord, Obad-Hai, Olidammara, Pelor, St. Cuthbert, Vecna), half of which are nigh-extinct (Erythnul, Fharlanghn, Gruumsh, Nerull, Wee Jas). Some from monster gods (Bahamut, Blibdoolpoolp, Eadro, the Great Mother, Ilsensine, Kurtulmak, Lolth, Maglubiyet, Sekolah, Tiamat) and gods from splatbooks (Al-Ishtus, Deep Sashelas, Ishtishia, Procan, Valkur, Yeathan). Some completely custom (Quasxthe, the Leviathan God, Inglip, antitheism, the Ancestor Spirits, the entire pantheon), some who are reappropriated Greyhawk deities (Dalya) or multiple Greyhawk deities merged into one (MAGG). So, because it is such a mess, I've been considering the merits of a completely new, custom pantheon, versus trimming some of the fat from this one and sticking with it.

Merits of the Default Pantheon:

• Most experienced players are likely to be familiar with it
• The main ones are in the Player's Handbook, so new players should't need much input or help figuring them out
• The pantheon is, in theory, professionally edited so as to make some modicum of sense, making DM fallibility less of a problem (Not that most other DMs are necessarily as fallible as I am)
• Creating a whole new pantheon is a lot of extra work
• Variety: if you can think of a concept, there's probably a deity in some WotC-published work that fits it pretty closely. It's like Rule 34, but for deities!

Merits of a custom pantheon:

• You can craft them specifically to evoke the mood you want them to evoke, to exemplify the world you want to run, to tell the story you want to tell
• The pantheons for most settings, including Greyhawk, are not Open Game Content, so you have to be careful if anything ever expands to media beyond just you and your players (e.g., if you want to put your setting up on the Internet...)
• You never wind up with the kind of confusing, muddled, multi-sourced mess that you do if you use the Greyhawk pantheon and then add or subtract some
• Creating a whole new pantheon is a lot of extra fun
• You can keep the numbers down and less confusing (if you allow every WotC-published deity, archdemon and archdevil, and Lovecraftian horror from beyond time and space, you'll swiftly wind up with an unwieldy mess of scores or hundreds of deities)

I asked the Playground, and a surprisingly large number of DMs use custom pantheons. I say "surprisingly large" because I've never actually played in a game with anything but the Greyhawk pantheon, except for one game that didn't go past one session where the very premise was "all the gods have vanished, go figure out what happened".

So now I'm inclined to craft a custom pantheon. Or, more accurately, to remake my current pantheon into a custom one. Some basic guidelines to guide us in as we think over this endeavour:

• It's okay if some of the deities betray their roots as published deities, though ideally they should be different enough from their origins as to constitute original intellectual property.
• I'd like to keep all the custom ones I've already devised, and ideally disrupt existing canon as little as possible in terms of Greyhawk deities that have featured prominently in the campaign (primarily Kord and Vecna).
• We'll try to minimize the number of deities, to maximize the probability that any players will give a crap; one suggestion in that thread is to keep it below 9, which is excellent advice, but I don't know if I'll actually be able get it below at least 14, given the previous guideline.
• Try to get at least one god of every alignment, and try to get every concept and domain covered at least once. (It's okay if we have some deities with weird and nonsensical portfolios, like Athena/Minerva, whose portfolio includes courage, inspiration, wisdom, civilization, law and justice, just warfare, medicine, commerce, mathematics, strength, strategy, the arts and poetry, crafts and weaving, skill, magic, owls, and the cities of Athens and Bath, among others. Actually, it's better than "okay"; we like realism, so that's actually great. We should make sure every deity has at least one nonsensical concept in their portfolio.)

Tune in a few posts from now when we actually embark upon this task!