Hi there! I have both and I use the Gucci key pouch more. It holds way more keys and I can fit a card or two in with the keys. I use the LV keypouch as a mini “wallet” if I want to use my mini pochette as a crossbody. LV key pouch is way too tight imo. In terms of price, the gucci key pouch is like another $100 but I think the quality justifies the price. It has a nylon lining on the inside vs just the canvas for the lv key pouch.
I'm not a fan of most gucci things and those key holders from LV are hard to come by (at least where I live!). I highly recommend going LV in this case because you will not only get something that is hard to find but something with better re-sale value too. Also canvas is a lot durable than the cloth that the Gucci one looks like to be made of?