Separate L1-B Application for Husband & Wife?

[cooltintin]

Me and my wife both work for the same company X and want to move to USA. I will be moving/working in a L1-B visa. My question : Is it mandatory for my wife to apply for L2 visa (and EAD) or she can apply for separate L1B visa ? I am not very sure about the advantages and disadvantages for L1-B and L2 and want some help! If we want to stay long term and both want Green Card or change status to H1-B which one would be more flexible.

Thank you very much in advance.