When it comes to value for money and overall effectiveness, it's hard to go past Rocket Spanish. There's a huge amount of learning material packed into each level for a pretty darn reasonable price.
You get what is essentially three Spanish courses: A 31-lesson interactive audio course which is great for listening to in the car, a 33-lesson "Language and Culture" course which goes into greater depth and explains the grammar, plus a suite of testing tools which work on your retention, pronunciation, writing and listening skills.
I especially like the interactive audio course: Each lesson is around 20 minutes long, and I'm constantly surprised at how much I learn in each short lesson.
If you're going to get just one Spanish course, this is my top recommendation. It gives you everything you need to get well-rounded Spanish skills, and it offers tremendously good value for money compared to other courses and software out there.
Amazing value for the price. You get an audio course as well as a grammar course so you don't need to buy them separately. One-off purchase (no subscription fees) and free updates for life. Friendly community. Works on PC/Mac, plus a separate app for iOS and Android. Free trial.
Only available online. (Digital download and physical versions with free international shipping available.) Not as polished-looking as Fluenz.
If Rocket Spanish doesn't tickle your fancy, Fluenz comes in a close second.
It also does an excellent job of blending grammar and interactivity so that you actually learn how Spanish works. (Compared to courses like Rosetta Stone which don't teach the actual mechanics of the language — Fluenz seems to have a bit of a vendetta against Rosetta, if you look at their sales material. Reeow! Claws out!)
The biggest selling point for me is the undeniable charm of presenter (and Fluenz founder) Sonia Gil. In each lesson you'll see her popping up to explain the vocabulary and grammar you're learning. Part of the Fluenz philosophy is to restore the tutor experience to the language learning course, and it works: She's smart, sympathetic, and encouraging, and I want to stick through the course just so I don't let her down!
Like Rocket Spanish, Fluenz offers a nice mix of explanation and testing. You end up with well-rounded skills in listening, writing, recall and pronunciation.
Fluenz Spanish doesn't pack quite as much into each level as Rocket Spanish does and the price tag is a bit higher, but it also has seriously high production values.
Earlier versions of Fluenz were only available as physical copies (so you had to wait for them to be shipped to you), but they now offer a digital download version. The price is the same.
Beautiful to look at. Engaging presenter puts the material into context. Lessons include tests which ensure you've mastered the material. Teaches grammar, rather than relying on gimmicks (watch out, Rosetta Stone!)
No free trial. Hefty download to get started. Harder to "binge" on material... you need to go through all the exercises. No grammar manual — you may need to purchase a separate book if you want a reference.
Michel Thomas was a Polish linguist and polyglot who spoke 10 languages, and whose students included Woody Allen, Bob Dylan, Princess Grace and Mel Gibson.
His method was pretty unconventional at the time: He emphasises "no writing, no memorising", and builds up your Spanish knowledge organically — word by word, until you can string them together to form quite complex sentences.
Along the way he explains important grammar and vocabulary points, but they're not the emphasis of the lessons. Don't expect to get a full and detailed run-down of various verb conjugations until quite late in the piece.
The great thing with Michel Thomas is that you very quickly feel like you're winning. He doesn't beat around the bush with polite niceties, he gets you started building sentences from the get-go. And unlike other courses that might artificially inflate your confidence (looking at you, Rosetta Stone), Michel Thomas gives you stuff that's actually useful and usable. So you really ARE winning.
The lessons are structured as recordings of Michel Thomas teaching real-life Spanish students. Some people find this structure frustrating, especially since the male learner in the Spanish recordings is quite slow.
Another complaint is that Michel Thomas himself isn't a native Spanish speaker, and his accent is quite strong and can be difficult to understand. You may need some additional pronunciation practice.
I really like listening to these lessons in the car — especially since I'm not required to write or memorise anything! If I had to learn by audio course, I'd choose either a Michel Thomas course or Rocket Spanish. (Or both!)
You'll feel like you're progressing quickly. Great for building confidence. Grammar is introduced gradually and naturally. You'll learn interesting tricks to remember things. Fun to listen to! Great for learning in the car. Not just dull repetition.
Pretty unstructured. It's hard to know exactly how much you've learned. Michel Thomas is not a native speaker, and has a strong accent. The structure (with other "students" in the recordings) can be frustrating and some people complain that it slows them down. Not good if you're more of a visual learner who likes to see the words.
There are a couple of things that Rosetta Stone courses are pretty good at. One of them is making you feel like you're doing really well. The matchy-matchy game-like quality of Rosetta Stone is fun, easy, and you'll feel like you're progressing quickly.
It's also arguably good at getting you to associate images of objects with the Spanish word for that object, rather than making you translate the word from English. This should make your recollections faster, in theory. I'm not super sold on this.
But when it comes to actually teaching you usable Spanish, the Rosetta Stone gimmick kind of falls flat. All you're doing is matching images to phrases. This means that you will only ever learn phrases that can be clearly represented in an image. Your conversations will be limited to shallow observations like "the girl drinks water". Seriously.
Rosetta Stone doesn't give you any English explanations, so it's left up to you to figure out verb conjugations and all the technical stuff you need to know to actually construct your own sentences.
Their angle is that it's teaching you language by immersion, and that it's how we learned our own mother tongues as children. It's really nice in theory and sounds good on the box, but it's unlikely to give you a working knowledge of Spanish.
It makes you feel like you're doing well. Good for your self esteem! The game-like quality is fun.
You won't learn much useful Spanish. Your skills will extend to stating the bleeding obvious. No cultural relevance: They use the same material for all languages. Expensive for the amount of Spanish you'll learn. You will need to buy another course if you want to develop fluency.
Ultimately, the best Spanish course for you is the one that you can stick with. Getting bored or discouraged and giving up is going to hurt your learning more than anything else — so whatever course keeps your enthusiasm burning is the best one for you!
Most of these courses are great for this. Fluenz is great if you like an interactive experience, Michel Thomas is fantastic as an audio course, and Rocket Spanish does both audio and interactive. Even Rosetta Stone might get you interested enough to keep going with Spanish.
But if you can only afford one course, I recommend Rocket Spanish. 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.
If you're just after an audio course, I'd go with Rocket Spanish (again) or any Michel Thomas product. Michel Thomas probably won't give you as good pronunciation as Rocket Spanish, but it's definitely great for confidence-building.