Discuss the wholesale blanks industry: Factory direct, custom labels. You can also use this forum to locate a wide variety of wholesale products including t-shirts, hoodies, mousepads, coffee mugs and other imprintable products.
The brands are actually pretty similar. Most of the brands you've listed I would consider more "high end" fashion type blanks.
I think if you have certain preferences, or if you think your customers may have a certain preference, it could be worth it to you to buy a sample blank from the various companies to see which one you prefer. That way you have first hand knowledge.
Some manufacturers have different styles within their line that stand out.
For example, American Apparel has a very wide color range. Article 1 has a eurofit t-shirt that is *very* soft. Continental has bamboo blank t-shirts that are more affordable than other bamboo blank t-shirt brands. Royal Apparel has nice relabeling and custom blank t-shirt programs, etc, etc.
I printed on some Pacific Sports shirts the other day. They are EXTREMELY soft. I think they are a good alternative to American Apparel. Less expensive also.
Which style of PS did you use? Are you familiar with a few of their styles or just the one you printed on? The big problem for me is that no style or even brand has all of the colors I want to print on. At the moment, I am using 4 different brands and am thinking about using even more! And I only have 12 designs!
Royal Apparel vs. American Apparel? 
