Cleaning up a 5V Switching DC-DC converter for low noise 5V output
You cannot avoid ripple on the output of a switching regulator.  You can somewhat minimize it, and you can shift it to a different frequency, but you cannot eliminate it.

A linear regulator has no ripple on the output.  There is noise on the output, but not ripple in the same sense as a switching regulator.   Of course, linear regulators have their own issues like terrible efficiency.

When I need something like relatively high efficiency AND super low noise I will use both a switching regulator and a low-noise, low-dropout linear regulator.  For a +5v output I will set up the switcher for a +6v output, and then use the linear regulator to bring that down to a clean 5v.  

Note:  not all LDO linear regulators are created equal.  Some have lower noise than others and some have lower voltage drops.  Pick wisely.  Sorry, I don't have part numbers handy.

Some people would use additional filtering on the output of the switcher instead of a linear regulator, but I find that such a filter isn't worth it.  Those filters are based on an LC topology and require large inductors and caps to be effective.  A linear regulator can be smaller and cheaper than a filter (but somewhat less power efficient).