F'lite in 31" size is now the standard travel suitcase for myself and my family, on occasions becoming a container for the 20" BF NWT. In spite of multiple carriers and ends of the world, its size was never challenged. While it is still in the pipeline in the market, some of the offerings are pretty expensive. It should cost under $200. Of course there may be some very cheap offerings too, that need to be checked as potentially fraudulent.
It appears that the F'Lite is being phased out. It's no longer stocked on most sites, and Amazon US only offers it for $400. (And it's not available in my country at all).