i would say paris you could use the eifle tower as a guard tower with a bunch of marine/jackal snipers all causing mayhem and urban warfare

infact the french and aliens would speak the same lamuage...  "bonjour" -(frenchy)  "bonjour" -(elite)

EDIT: oh and i think that paris would be scary infact if you pass the eifel tower it would be a death zone there so many snipers imagine it       

/\--------  :] ----------      -----X[------