I do not mean to give offence, but sometimes think choice has killed logic in cycling. Unless you have a Brompton or similar which requires a specific bag, then you can go into a sports or bicycle shop, try, buy, and be out of there 10 minutes later, It really isn’t that hard. If there’s no sport or bike shop near you, try the internet. Unless you are a brand slave, just pick one that is the size you want.

Never spent more than two minutes on handlebar bags, which are pretty much of a muchness, given they tend to be for useful things like maps, phones, suntan lotion etc.