Verified answer

The meanings of these two are the same, but もまた is more used in written language. Actually I myself never use もまた in conversation.

もまた seems to intensify what was said just before it (in this case, "I") than just も.

Since もまた is more formal, である seems to fit the context well. Just my feeling, though.

Momata sounds a wee bit stilted. They mean exactly the same thing.

Another example:

1. これも　また　起こりうることだ。

2. これも　起こりうることだ。

Here, there is a noticeable difference in nuance (at least so it seems to me) that might dictate different usages. If I try putting the difference into translation, they might be something like:

1. This is yet another possibility.

2. This is another possibility.

Having said that, the difference is only slight.

また is means "again"

彼はジャズが好きだが、私もまたそうだ。 he likes jazz, but how wonder i like jazz too

彼はジャズが好きだが、私もそうだ。he likes jazz but me too