I personally like both of those, although DBpoweramp is a slow process and a bit of a resource hog at times. Another good alternative that I have found is "4Musics Multiformat Converter" which you can trial for 15 days.
http://www.4musics.com/wav-mp3-wma-ogg-converter.htm
It features a great GUI as well as being easy to use. Hope it helps.
