Union organisations
Well, these aren`t really much in opposition to each other. When the Planar Cartographic Society wants to map it all, few would argue against it, even the factions of Planescape. Granted, this might be seen as something the Guvners would want to do, but the specialised exploration-aspect of the PCS make it far more appealing. You do not have to accept a full philosophy of law as the members of that faction does, and "adopt" its enemies. Some of my players greatly enjoyed this freedom of being a Surveyor.
The Garrote appeals alot to more evil-aligned characters, as they are given access to magnificent epic-level secret "poison" like mortu, and the like.
The Gleaners are one of the best adventure hooks I have for epic-level characters. The obsession with artifacts make them very interesting in two ways:
1) Making players involved with direct artifact-hunting at many planes.
2) Allow players to actually BORROW artifacts from their Penultimate Vault.
The Godkissed are also nice for adventure ideas, but really..this is not really anything but a recipe for disaster, as the various factions here squabble so much. A society like this, with few (if any at all, that is) set goals makes it appeal little to many of my players (and I`d imagine to few others, too).
Those are just few examples, but generally it is easier to subscribe to one of these(at least for my players) than huge set (Sigil-based)factions encompassing not only most planes (which can be a good thing), but also a wide range of opinions and political sympathies, in many cases. Even a member of the freedom-loving faction Free League in Sigil can`t be said to have true freedom, as they will almost automatically become enemies of factions like the Harmonium.
Most of the organisations based in Union would even accept members from multiple other organisations.
It has been said many times that the idea of an "epic" city is ridiculous and laughable. I can`t agree with this. Yes, the vast majority of Union is still not "epic"-level, but the idea that it is a city for such characters makes it attract such characters from all worlds, making the organisations there stronger and more succesful.
The organisations of Union is what makes the city work to me. Yes, a huge marketplace is nice, but can`t cater to the needs of epic characters(or any campaign with them) by itself (even if made to be the only place in the multiverse that can potentially sell +7 swords).
And...SOME epic characters do like to work even as Union Sentinels in their time between adventures, as long as they get the flexible spare time to actually partake in such ventures. The position as a Sentinel is a truly honourable one in Union, but also potentially in many other worlds. I`ve noticed that these Sentinels are what most people vehemently attack the city for on these boards
