Hi there! Another guild newbie here ^^.
I tend to run LJ with Master Queeg and Alison Dade. Queeg provides LJ extra mobility in addition to the promises upgrade that, as it been said, is really nasty with her. Alison can punish enemy models that perform attack actions near her and also can help LJ survivability healing her. I have nice results with this combination in casual games with a couple of friends.
If you have the opportunity, pick the brutal effigy, which is useful with almost any guild master.