I have experience with both. Here's my take for what its worth.

A versus M

A is addictive (if large doses are taken over long periods)
M is not

A does not make you gain weight
M can (if you get the munchies, etc.)

A is legal
M is not

A has no taste
M does (this is a pro or con depending if you like to smoke)

A is not linked to cander
M is

A could be used to excess causing overdose (if you wanted it to)
M would be difficult if not impossible to overdose on

Personally I do not smoke marijuana because it is illegal and I did not enjoy it enough to risk any encounter with the law. If you're going to break the law, make sure its worth it.