If the previous options are not quite what you are looking for, consider an under the sink water filter. This type of filter is attached to the cold water line underneath the sink and the water is retrieved through a separate above sink faucet. This system provides a better water flow than the faucet mounts
These filters are out of sight and contain cartridges that need to be changed only twice a year. These cartridges may be difficult to get at under the sink and therefore difficult to change. You may not want to install an extra faucet in your designer sink, a usual requirement of this system and you will need to install a unit for each location that you require filtering.
The initial cost can run over $100 for the filter and another $100 for installation by a professional plumber.