I can't really speak for the European market, but I know in the US sometimes it makes sense to go with the alliance that DOESN'T have a hub in your airport, at least from a cost perspective. For instance, it may make sense flying in the DC area to go with ST or OW, as "hub attacks" will often cause DL or AA to have a fare sale from UA's hubs (IAD). It's also a benefit having several airports with the same city code, as fare sales will sometimes be applicable from "WAS", making DL's network from DCA an attractive option. Again, I don't know if this transfers well to London (Does LH or KL offer fare sales from London often? Is there a *A or ST carrier with a hub or semi-hub at LGW or LCY?). It may also be worth noting that someone looking for status on segments may want to take one-hops instead of non-stops, which is easier from a non-hub.