For us, it's a matter of taste. We raised 25FR's in the Spring and 25CX in the fall. The CX were on a fermented feed regimen that did help with the quality of their poo - quantity was still a heck of a lot. The FR's were more interested in what was going on around them than our CX - but was it because of the shorter/longer light days? Who knows.
I've determined that the CX is a great bird overall - but truthfully, I don't find the flavor that different than what I get at our local grocer (Amish free-range birds). I prefer the flavor of FR's - has an almost nutty flavor to the meat. Again, the FR's did more free ranging than the CX; but the CX got fermented feed so one would think it'd be different than the grocer. However, the FR's have a noticeably thinner breast meat - it's not the double breast like the CX. We're fine with that. There is still plenty to go around our table.
I preferred processing the CX - a LOT less feathers to deal with. But more ick factor on those feathers. The FR's were simply fluffy; all around fluffy and left me loads of feathers everwhere! The frame of the FR was also slightly more vertical, which meant that my husbands hands didn't fit inside as well - the CX has a more horizontal carcass space, so husband could fit his broad hands in there easily.
The FR's we grew out did well in the heat - but I found I was watering them more than the garden! Once temps hit above 80, they seemed to struggle to keep cooler - we put fans in the run and shade cloth and extra waterers. The CX's did exceptionally well in the cold (coldest October on record) - and didn't have any problems with them at all. Although I think the cold kept them from growing as quickly, as it took an additional 10 days to reach the weight we wanted - or about 125#'s more feed.
We're not interested in growing out 25 birds again. For our run, 12 is a much better situation. So it's not likely I'll be raising FR's again, unless I can find someone to split an order with me, or find a different hatchery. That's the research for this winter (post Christmas)! Good luck!