I've used all kinds of different brands of buiscuts, both name brand and "off brands". I've never noticed any difference. After all, the whole point of buiscuts is to have a fairly sloppy fit and the buiscuts swell to align the parts.
The big secret is to keep them dry. I like to keep them in a ziplock bag inside a plastic jar.
If they do get damp, they might not fit easily into their slot. Just microwave them for about 20 seconds and they'll shrink right back down.
I can't disagree with Ralph. I have seen some that wont fit because of moisture that is why I like to buy the PC biscuits. The containers that they use are easier to keep the biscuits dry...at least for me.
John Lucas www.woodshopdemos.com