Trying to choose between computer based training packages can be a difficult thing to do. There are different types, things such as CBT nuggets which involves someone explaining things really well in interesting videos. These have been criticised in that they do not cover all of the information that you will need but about three quarters of the course material. They have been found by a lot of people to be interesting, entertaining and informative with good examples, analogies and explanations. However, if you prefer something which just puts across the facts and starts with the real basics then Train Signal could be best. Reading various reviews has led me to conclude that a combination of both tends to be good for most people and it can depend on which course you are taking as to which is best. This is not a lot of help really so I think that reading reviews specific to the course that you are doing will probably help you to draw the best conclusions as to which will suit you the best.