Judge against a written standard
How a sample feels in your hand tells you little about whether buyers will keep it, return it, or complain. Decide what a good version of your product looks like before the first sample arrives, and write that standard down.
Build the standard from evidence rather than taste. Reviews on competing products already tell you what buyers praise, complain about, and wish for. Turn repeated praise into things your sample must match, repeated complaints into problems it must solve, and requests into features worth testing. That list, not your preference, is the bar every sample is measured against.
Order, test, and pick
Write the tests before any sample ships, so every supplier is judged identically. A test that changes between samples is not a comparison.