AM/MA and NP in analogy to P and BPP
This is of course a very subjective matter, but here is something that might be interpreted as saying that $\mathbf{MA}$ is a closer fit: The same assumptions that imply that $\mathbf{P} = \mathbf{BPP}$ also imply that $\mathbf{NP} = \mathbf{MA}$, but those assumptions are not known to imply $\mathbf{NP} = \mathbf{AM}$.
In addition, the assumption that $\mathrm{promise}\mathbf{P} = \mathrm{promise}\mathbf{BPP}$ implies that $\mathrm{promise}\mathbf{NP} = \mathrm{promise}\mathbf{MA}$, but is not known to imply $\mathrm{promise}\mathbf{NP} = \mathrm{promise}\mathbf{AM}$.

However, there is an alternative view saying that $\mathbf{MA}$ is the non-deterministic variant of $\mathbf{BPP}$ while $\mathbf{AM}$ is the probabilistic variant of $\mathbf{NP}$. The foregoing facts can also be interpreted as evidence for this view.