What classes?
Dranik Loyalists is decent if you plan on doing the Anguish quested armors, some of which are very nice due to mod2s and other effects on them for many levels. I think both of my 80+ War still wear the legs due to the Riposte+8% mod, and have several toons with the chest piece for the clicky ... btw, Monk with AoA chest clicky can solo OMM eventually, since the clicky will remove his recourse buff. Personally I've always kept Rangers on the debuff job, as for some reason, no matter how much practice, even with whole raid in masks, at least one, if not multiple people, will miss the mask click. Ok, side-tracked on Anguish for a second.
Only problem with Dranik Loyalist faction is it takes a while (many hours) of work, unless you got an PBAE weapon and a high level helper to keep aggro and AE them to death once the lower level does some damage to them all. Even then it's about a days worth of work to get enough mobs killed to get to Ally. On my War, I soloed them at 70 in DS, and would usually take about a week of 3-4 hrs / day to get there, depending on how buffed, and how often, I'd use the Riposte disc, or if I'd box a Mag or Dru to keep high DS (and heal proc from Dru) on me, but I didn't do that much as the 1st War, I just started trying to box and wasn't very good at it yet, and the 2nd was the highest toon on that server.
Enough about OoW, as Dranik Loyalist is the only faction to worry about. DoN progression, you can go either way, Norathian Keepers or Dark Reign. Generally it's better to stick with what your side your toon is closer to, to start with. Although not necessary, it saves about 1 faction level of work to do so. Also, if you have both good and evil toons, you can earn both crystals then.
EDIT: The reasons it doesn't really matter, is the raid items can be looted from either raid expedition. They are exactly the same raids, other than the NPC used to start it and the faction token you get as a reward. Raid tokens do practically nothing for faction (probably 1 faction point / raid token, as I've turned over 50 at one faction level without any change in faction), it's about the same as killing NPCs guards at the camps, and takes way too many to move a faction level, versus doing group missions, that only require about 5 tokens for most faction levels. And as the items are lore, but different from each side, you can get two of everything by buying from both sides, which just requires an invis, as the merchants do not drop your invis like most merchants when browsing / purchasing items and sell at best price (indifferent faction) while you are invisible. If they were on different accounts and were planning on boxing them, then it makes more sense to stick to one faction, but even then, I tend to go with whatever side they're closest to, to start with, as the missions don't take too long, and I earn crystals on both toons from both sides, plus whoever else I get in on taskadds for the wins.
I don't really recall any critical factions with DoDh, nor PoR. Both may of had some, but just doing the access missions (that are no longer needed) would get you more than enough. DoDh spell are missions are still descent to do for spells / tomes, but on a non-TLP server, you can find someone who can make them, if you have the cash. I generally just do the missions, as most of them are pretty easy by todays standard, rather than spending a 50-100K for needed spell / tome.
TBS has some good factions. Lately, I've just been doing the Pirates one (
Blacksail Smuggers) via the Hand Aug quest, and getting the Rk Is of their spells. Previously, I'd do the Solteris access series which by itself would get you close to Ally in the Katta faction (
Combine Empire Merchants) for Rk II spells / Tomes as well as some other descent items not to mention Power Supplies.
TSS factions aren't really important any more, unless you plan on requesting TSS raids, then basically, you just need to do the access series of quests and a few of them several times to get enough faction. In general though, there's nothing really important there, 'cept for the Wraithguard factions (
Wriathguard and
Wraithguard Leadership) for doing a few quests with nice rewards, like the
Runed Diamond, and the
Battered Shield of the Fallen Guard.
SoF mainly depends on class. Almost all will need Ak'Anon Strike Force V, and all will need if planning on doing SoF armor upgrades. See
Rasper's Guide for which factions each class needs for spells / tomes. The faction route is often faster and easier to get the Rk IIs than waiting for the rare drops of the Rk Is that drop. Lots of descent equipment drops while working on these factions as well from nameds. CoV faction requires Crystallos access to work on (didn't they just unlock it? If they did, lots of great drops there as well, and fairly good spot to get most of the higher 78-80 level Rk II spell / tome drops). Don't forget the daily faycitum tasks as well to help out with any of the SoF factions that need work. EDIT: Faycitum Merchant / Quest Giver: http://eqbeastiary.allakhazam.com/search.shtml?id=29799
SoD doesn't really require much faction work, and none, if you get someone with the pre-requisites to grab the tasks needed for progression. Even if you don't have someone, simply doing the pre-requisite tasks will get you plenty. See
Rapser's SoD guide or
Alla's SoD Guide EDIT:
Cirtan, Bayle's Herald may require some work, if you plan on doing any of the themed augs.
EDIT: Underfoot I'm not sure about.
Yther Ore.
Edited, May 17th 2011 3:28am by Yther