If you're looking for a rock-solid German course that ticks all the boxes but doesn't cost the earth, then it's hard to go past Rocket German. There is a huge amount of learning material packed into each level, for a pretty darn reasonable price.
In the first level alone you get 29 podcast-like audio lessons, 30 "language and culture" lessons, and a bunch of interactive exercises to help you build your listening, writing, recall and pronunciation.
If you're heading overseas and you need a quick introduction to German basics, the Interactive Audio Course teaches you a surprising amount in a short space of time. The lessons are around 20 minutes long, and perfect for listening to on the way to work or at the gym.
If you're only going to get one German language course, this is my top pick.
Visit the Rocket German website or read my full Rocket German review
If you're just getting into learning German, Duolingo is a pretty good place to start. It's essentially a really big language-learning game, where you complete exercises (fill in the gaps, translate the sentence) to complete levels.
It's not particularly useful as a crash-course in German if you're heading overseas. For instance, it's quite a few lessons before you learn the basics of "my name is..." But if you're in this for the long haul, you won't mind starting off learning sentences like "The boy is a child".
The grammar points at the beginning of each level are a welcome addition and help you understand a bit of what you're learning, but you might want to pick up a textbook or another language course if you want to "fill in the gaps".
You can use Duolingo both on your computer and through a free app. It also has a really nice community forum.
If you're interested in learning German in the car, at the gym, or you're just a particularly big fan of podcasts... GermanPod101 is a good way to go.
They have a staggering array of podcasts that you can download and put on your phone, covering material from beginner through to advanced.
It's a monthly subscription service with different pricing levels depending on whether you want all the bells and whistles (line-by-line audio, additional exercises, flash cards) or just the podcasts themselves.
Like Rocket German, Fluenz works your German knowledge from all angles with a range of interactive exercises, so you come out at the end with well-rounded skills in listening, writing, recall and pronunciation.
Fluenz’s “thing” is the on-camera tutors. They pop up now and again to explain the vocabulary and grammar you’re learning. Each lesson also comes with a range of game-like exercises and conversation practice.
Fluenz is downloadable software, rather than an online course like Duolingo or Rocket German. It doesn’t seem to pack quite as much into each level as Rocket German, and the price tag is a bit higher, but it's also a lot more polished.
Ultimately the best language course is the one that you enjoy and stick with. If you get bored and give up, it's all over. So find the one that best suits your learning habits.
If you’re going to buy just one course, I recommend Rocket German. It really does pack the most value in. You get an audio course for the car, a full grammar course, and all that interactive material as well. You can discover which method works best for you without needing to purchase other courses.