I'm from Canada and I had a good experiene with the NY Balenciaga store. I ordered a Black City and a Black First from them right before they closed. I knew they hadnt processed the order yet so that night I called and left a voicemail cancelling th Black First because I decided to purchase an old one from Sweetsparkle.
Well I just got my shipment and obviously they did not listen to my message and lo and behold, they shipped and charged me for the First as well! In addition, I had to pay for $370 in duty! I was pissed of course, so I called them up immediately. They gave me no hassle whatsoever, I will ship the bag back to them COD get refunded for bag and they will dispute the duty charges with UPS. So even though they made a mistake, they gave me no hassle whatsoever to return the bag and get refunded!
So long story short, department stores have great return policies but I really liked the service at Balenciaga. I dont think you can go wrong iether way. But if you want a longer window where you can return for a full refund then go with the department stores. Also they take longer for repairs I find so both have their good and bad sides.