Be aware that you don't have just one credit score. There are many scoring models (even just among the FICO's) that creditors use. Typically for a given model you have a score with each of the 3 major CRA's.

Best is always highly subjective. Make sure you state exactly what you mean whenever you use "best". If there was one universally best site then everyone would use it and no one would use the alternatives. What are you specifically looking to do with the scores? If applying for credit, consider the specific scoring model and CRA('s) that are used for that product. What are you willing to spend?

myFICO will give you 6 or 19 FICO's depending on the product selected.