I'd go for a cheap (but branded) luggage as they get trashed the first time it's checked in. The way they are handled you'll probably need to get a new one every year or so anyway so there's not much point going for the top end stuff. It used to be the case where the airline will cover for damages and replace the luggage so it was worthwhile getting a good one (so they can replace it with the same brand) but these days they do everything they can to get out of any liabilities.