In my experience, ASC has provided higher quality construction than GIK, but at higher cost. I’ve used both companies happily and also have a few BAD panels from RPG and some diffusers from Vicoustic. I have not used ATS yet; didn’t know they existed, but I’m glad to hear about them.
The thing I really like about GIK is that they publish test results for every product, so you can see what the absorption is at different frequencies. It’s easy to determine from their Web site that, e.g., a 4" thick panel (made by anyone) won’t do much below about 80 Hz. The GIK Soffit Traps go a bit lower.
I would caution you not to use only "acoustic panels" that don’t include some reflection or diffusion. ASC uses reflective strips under the cloth of their panels to avoid over-deadening the room; GIK offers their Alpha panels and range limiter option to do the same thing; RPG BAD products are designed to balance scattering and absorption. A room using only plain absorbers easily can sound too dead.
The thing I really like about GIK is that they publish test results for every product, so you can see what the absorption is at different frequencies. It’s easy to determine from their Web site that, e.g., a 4" thick panel (made by anyone) won’t do much below about 80 Hz. The GIK Soffit Traps go a bit lower.
I would caution you not to use only "acoustic panels" that don’t include some reflection or diffusion. ASC uses reflective strips under the cloth of their panels to avoid over-deadening the room; GIK offers their Alpha panels and range limiter option to do the same thing; RPG BAD products are designed to balance scattering and absorption. A room using only plain absorbers easily can sound too dead.