They are indeed both compressed formats. Of the two I have a clear
preference for WMA as MP3 encoding seems more uneven in terms of frequency
response.
However, I now use Ogg almost exclusively as the quality / compression is
extremely good. 192 kbps gives reasonable recordings although I tend to
encode at around 320 kbps. 128 kbps is far too low in my opinion to be
commercially acceptable as the quality just isn't good enough.
Try and avoid converting from one compressed format to another as all
compression algorithms lose different elements of the sound and you'll always
end up with something worse, never better.
Steve