Theoritically speaking, where in Sirius could you get the most factions involved in a brawl, considering ID restrictions, including Corporations, assistance clauses on individual IDs as well as bounty hunting clauses?
Maybe the Taus, around a Freeport?
GRN, BAF, BIS, LN, LSF, Council (???), IMG, CR, HF, Junkers, OC, Hackers, Rogues, Xenos, Gaians, Mollys, Ageira, DSE, Universal, Synth, Cryer, Planetform, Gateway, Bowex. Interspace, BHG, Core, and probably more...
Magellan.
What joe said, Magellan. Tau 23 isn't far off though.
either gamma, or the zoner war MkII
As Joe said Magellan.
I'd say Sigma-13 is a good contender as well though, as was shown during Garret's spontaneous event a little while back. In S-13 there can be KNF, KPT, RM, BDM, Bundschuh, Unioners, LWB, Hessians, Blood Dragons, Golden C, Hogosha, Farmer's Alliance, Corsairs, Outcasts, Core, the Order, Nomads and more.
Either Magellan or Leeds.
Magellan for sure. It's the primary disco battleground.
Sigma-13 and Tau-23 are also solid choices.
Yeah like others said Magellan, Sigma-13, or Tau-23 all are in the ZOIs of multiple warring groups.