My choice is [IVONA TTS][1]. It is amazing. [It has a free app for android][2]. I use it to listen to the new words and their example sentences that I have listed and also to listen to the interesting news and texts to improve my listening skills.  I use it in combination with ["Voice reading"][3] app. 


  [1]: http://www.ivona.com/us/
  [2]: https://play.google.com/store/apps/details?id=com.ivona.tts.voicebeta.eng.usa.kendra
  [3]: https://play.google.com/store/apps/details?id=com.noinnion.android.voicereading