Learning to speak Spanish can be quite fun and easy if you have the right tools, if you have the right information you can make the right choice for you. There will be no clear cut winner, but the differences and advantages of each course will be highlighted, and the right course for you will be apparent.
1. Synergy Spanish
Synergy Spanish is strictly for the absolute beginner who needs to learn how to speak Spanish with the utmost urgency, think a businessman on a plane flight to South America trying to cram as much in his brain as possible. This by no means is a knock on the program, it's just that as software to learn Spanish goes, it's a kick-start to get you communicating the language as quickly as possible, and as such ignores area's such as reading, writing or intermediate to advanced material. So the core advantages are that it's fast working for when you need a basic command of Spanish, and it's very affordable at under $ 70. Disadvantages are that it has no advanced material and the main focus is on speaking Spanish as opposed to reading or writing it.
2. Learning Spanish Like Crazy
Strange name aside, the Learning Spanish Like Crazy is a very solid program. It's audio only, so you will not be able to read or write after finishing LSLC, but most people want to learn Spanish to SPEAK it, right? LSLC is quite similar to Pimsleur in it's approach, which may or may not mean anything to you (I liked Pimsleur so I think it's a good thing). Disadvantages are that, again, it's audio only.
3. Rocket Spanish
Rocket Spanish is perhaps the most well known of the 3 software to learn Spanish programs here, they have an overall focus that includes both audio and reading / writing parts to it. It's probably the best solution for people that want an overall Spanish education as opposed to only being able to speak it. At $ 99 it's very similar priced to both Synergy Spanish and LSLC, so if you are wanting to put a long time investment into Spanish then I'd go with Rocket Spanish.