FACT - A single piece of Atlas 40" Flex track is $22 MSRP, Gargraves 37" Flex track is $10. That's 2 GG for the price of 1 Atlas, any discounts or For Sale items on the forum for either brand will still be close to 2 for 1.
Ross carries GG Flex Track at $6.50 (min of 10 pieces), but like I stated in my above post, it's not the same design. Public Delivery Track carries Atlas O Flex track for $15 each or case of 12 for $185. I saw one listing on the For Sale forum for a case at $150, that's still $12.50 per section.
I bought a piece of Atlas Flex from my LHS (at full MSRP) a while back because I needed a piece of flex track and they didn't have any GG. It's nice, no question, but twice as nice, subjective.
A quick measurement (I had to get down on the floor with my micrometer to take measurements, so I may have not had them held flat against the tie surfaces) shows the Atlas ties are .189" wide and .256" thick. The Gargraves ties are .329" wide and .230" thick, thinner in thickness than the Atlas ties and visibly noticeable. Where Atlas wins out is in the solid nickle silver rail. If Ross ever offers flex track designed like their curved sections (folded under, not embedded into the ties like GG) then more testing would need to be done to see which brand is quieter. If Ross could be talked into making their ties narrower, then we might have a clear winner.
Ross and GG look alike at first glance, put a section of Atlas track in between and you can see the difference. If you look at GG track from the side, you can see the shine of the GG rail between/underneath the surface of the ties (Not so with Ross track).
In the end it depends on what you want for your money. I've got about 15 Ross switches on my layout, that's a lot of bucks no matter which way you look at it. After spending that amount and seeing how good they perform one can't help but think about buying their curved sections too. I fill in any gaps or long straight areas with GG flex track. My single piece of Atlas flex track is on a shelf where I store my freight cars, waiting for the next call to duty