true they are all close in quality... BUT the Manta fits like it was designed specifically for the Wee. pretty amazing for an "off the rack" item these days. most of us who have them bought it primarily for that reason after diligent googling. :biggrinjester:It's pointless to recommend anything. It's up to you.
On a group ride, I've never seen two bikes using the same tank bag.
I have the Manta (the small one) and it does indeed fit very nicely and is fine for holding a wallet, cell phone, and water bottle (and probably not much more). For day rides it's perfect. It will leave scratches in the tank paint though, so I stopped using mine and will likely go with one of the Bags Connection bags that don't touch the tank.JR Manta works nicely... recommend you don't get the small one, the big one is not that big!