The best replacement for rosetta is pimsleur.

The best alternatives to rosetta are rated as following:
★★★★★  pimsleur
★★★  fluenz
★★★  ensemble
★★  tell me more
★★  aurora
★★  duolingo
★  berlitz
★  bl21
★  instant immersion
★  fireface
★  ad16x
  duet 2
  rocket
  ad 16x

Your alternative for rosetta is not listed? Suggest!
Speaking about rosetta, one probably shouldn't forget about snow leopard.

Other search terms related to rosetta and their ratings are:
★★★★★ snow leopard
You have in mind a companion for rosetta and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of rosetta in all years. Click on graph for more.
rosetta
pimsleur
fluenz