Maximum "nominal" supply voltage for the 4000 series is 15V. You can push it by running them at the absolute maximum ratings, but that generally isn't a very good design practice.
Unless you are using rail-rail in/out op-amps, they will need at least a volt or two of headroom, so you won't be able to power them from the same rail potentials as the analogue switches, if you intend to run the 4000-series analogue switches to their limits. The DGXXX series on the other hand can run on rails up to +/-22V, so they can be powered directly from the op-amp supply rails. That's generally a lot more convenient.