"Are all Mini 14 Barrel Stabilizers or Barrel struts the same?" They all work the same, or accomplish the same purpose.
"Who makes the best one?" Different folks here have different brands and some have made their own. This is a Ford/Chevy question with the answer being, "It depends on your own preferance".
Personally I bought an Accu-Strut for my "skinny" barrel 580 series. I like how it looks, like what it does, and got great support from the vendor (NEST Engineering) who is in this forum.