I have a large collection of stickers and would be ecstatic to add some Kiwis to it. Smaller stickers are easier to store/display in sticker albums/card sleeves for the autistic collectors such as myself, but I wouldn't complain about some large ones.
In regards to sticker sizes from my personal experience: 1 to 2.5 inches will work for individual stickers in card display sleeves, 1 to 3 inches works for a photo display page with cling film if doing round cut. "Kiss cut" (or the stickers edge is the outline of the design itself) is more forgiving on size for card sleeves, because the sticker can be rotated to fit into the sleeve. Large stickers being 3.5+ inches would be good for sticking on cars or local boards where people are allowed to post whatever they like.
Branded or unbranded doesn't matter to me, because I'm keeping mine in a sticker album. The exception to that would be if I buy a large duplicate of one of the designs. That large duplicate would be used to enrage local troons, so branded would be perfect for that purpose.