While the game mechanics are the same - it's the Cypher System -, the game worlds and settings could not be more different from another. So it effectively depends on what kind of adventures you want to play and what kind of atmosphere you want at the game table.
The world of Numenera provides a wide variety of possible settings already and you could replicate aspects of other game worlds there. But if you - for example - would like to play an adventure in a superhero setting, it will very likely turn out differently if it's initiated via a stand-alone setting derived from the Cypher System Core Book, a recursion in The Strange or whether you're playing in the Ninth World, with superpowers being the effect of a powerful Numenerian artefact.
So in my opinion it comes down to providing a lot of inspiration and having additional Foci & Descriptors ready. I personally like these books a lot and our games of The Strange always play out very differently from when we play Numenera. I haven't created a pure Cypher System setting yet - been sporadically working on an adaptation of Mass Effect -, and am still looking forward to a game of Predation; basically one needs a lot of time to realize all the possibilities these books offer, too :D