How do you judge the best acoustic panels?
Fit the panel to the space.
If you are in a recording studio, you will want a range of panels that go as thick as four inches, to address the full sound spectrum.
For an office or restaurant, you are only addressing the mid frequencies to high frequencies. A one inch acoustic panel is more than enough.
Acoustic panels have to look the part.
In a studio, acoustic panels don't have to look that great, its expected that a studio is functional space. When you are entertaining customers in your office or restaurant, the acoustic panels have to look great.
So how do you choose the right acoustic panel?
The easiest way is to look at the supplier's or manufacturer's website, and if they look like they have installed a significant number of panels in an environment that is similar to yours, go with what they recommend.
Make sure the acoustic panels are made and supported locally.
Purchase your acoustic panels locally. Support local business and get local care and installation.
Don't get hung up on the stats.
Don't overdue the math. Start with the volume of the room times .03 to get the ideal square foot coverage, then choose an acoustic panel that will provide .8 NRC for offices and restaurants. Keep it simple. Calculate the proper square footage for acoustic coverage.
Understand the concepts, just a little bit.
If you understand how sound works in a basic way, you won't have the expectation that one 2x4 acoustic panel placed in the middle of room, doesn't attract and draw sound in like a blackhole. If you understand the concept you will understand that you need good acoustic panel coverage.