Have worked both, prefer GOX  

Fact is a lot of flights don't use O2. LOX cooks away slowly but surely, GOX doesn't. GOX is a lot less trouble and hazard to fill up--Hardest part is muscling the cart out to the aircraft, which isn't very hard. Personally, I'd rather do a GOX service maybe once per hitch than LOX. Also, for any management that's paying attention, GOX has to be cheaper in the long run because your LOX sits in the storage container cooking away...like I say, slow but sure, whether you use it or not. GOX cylinders just sit there full until you need them.