I can't think of anyone better suited than Simon Rattle to conduct Ravel's Daphnis & Chloé. Sure, the City of Birmingham Symphony Orchestra does not have the stellar reputation of its counterparts in Vienna, Paris or Berlin, but frankly, each of these symphony orchestras have their fortes, and not so fortes as well...
What matters is how well suited the orchestra's (and the conductor's) fortes are to the compositions, and in this case, Simon Rattle's masterful musicianship and conducting skills are a perfect match.
The only "better" version of Daphnis & Chloé I've ever heard was live, in Paris, with Sir Simon as the guest conductor.
As regards the Bolero, there may be better versions (depending on taste) but this one, unlike Karajan's (the timing of the snare is consistently off, way behind the Berliner's) or Abbado's (classic perfection) catches the ear with its lighter touch, and dare I say 'swing' (listen to it!).
Ultimately, as well it should, it all boils down to Rattle, who stands out among other conductors of his stature, as the one who gets Ravel's colors, and is best suited to translate them with the orchestra, and for a modern audience.