@Hp289 posted:Soooo...which is a better track overall regarding construction, not looks.
All of them (Ross, Atlas, Gargraves), that's why you see so much mixing.
We can leave switches on the side since most of us agree Ross is the best choice in switches.
Some people choose between brands because of the tie size and spacing and think one brand looks more prototypical. Some people choose based on track noise on a layout. Some people like flex track for various reasons but not all flex track flexes the same. The point is that is seems most people choose based on aesthetics or logistics.
I'm currently building a new layout and I have around 150' of Atlas O track. The solid rail is what I like but I pay a hefty premium for this track, it is a nickel-silver alloy subject to the precious metals market with plastic ties that can be run outdoors. I have close to 200' of track to buy for the new layout so I'm starting to think about mixing in more Ross sectionals and Gargraves flex. They all can mate well with each other.
See how the mixing gets started? 
Edit: I forgot about mating Ross and Atlas, since you brought up those nails holding down Ross track. When I mate Ross and Atlas I use the Atlas track clips as they match the Ross track profile pretty well. Sometimes it is necessary to remove the first nail or two to slide the clip on to the Ross track, so there is a benefit to being able to remove those little nails. Sometimes I just have to lift them a little, slide the clip on, then push the nail back down into the tie.
Coffee is kicking in so I'll finish my thoughts. 
I would use Ross and/or Atlas sectional curve pieces as they are consistent, Gargraves are close but not consistent.
