It depends to your specific application. For example, electron mobility of graphene layers is more than that of MCNT due to their layered structures. However, MCNTs are more robust than graphene sheets and suitable for mechanical reinforcement or flexible electronics.

It depends to your specific application. For example, electron mobility of graphene layers is more than that of MCNT due to their layered structures. However, MCNTs are more robust than graphene sheets and suitable for mechanical reinforcement or flexible electronics.

 I don't know which properties are you comparing with. In fact, there are cases in which graphene outperforms MWCNTs. For instance, in polymer matrix nanocomposites, graphene reinforce more than several times (even ten times also reported) than CNTs in terms of strength for the same quantity in wt% of reinforcement.

It all depends on the properties you are interested to compare. Or the application you need.

This is entirely dependent on the application. Are you looking to use this for electronics or mechanical? Is it in a composite form or in pure form? What are the tolerances and specifications for your need?

With answers to the above I am sure the community will be able to help you identify the right type of material requirements. But, the two systems you are trying to compare have vastly different and somewhat unique properties, although based on the same hexagonal carbon sheets to start with. Nominally, it is type selective SWCNT that is compared with graphene .... not MWCNT.

It depends on what you mean "better". In any case you have to consider defects as an important factor that affect the properties of both graphene and cabon nanotubes. Moreover, you  have to take in account that graphene is 2D structure, while a nanotube is 1D. In general grounds some properties are almost the same, but some others are totally different. For instance graphene is semi-metal, while Carbon nanotubes are either metals or semiconductors, depending on their chirality.