Completely, Utterly, or Tremendously excited?

Of those three my choice goes for tremendously excited. Why? To be honest it is my gut feeling, and the ngram shows it is by far the most popular choice of the three. But now I’m going to engage in a bit of ex-post rationalization.

Utterly and completely are synonyms; utterly is more emphatic. So my feeling is utter and complete work best with things that can be, well, complete: destruction, failure; even nonsense can be complete if there isn’t a grain of sense in it. But it is difficult to think of a limit to excitement, so utter and complete don’t work so well with it.

On the other hand, tremendous is as per Merriam-Webster very large or great; very good or excellent. This goes well with excitement, as it does with popular and funny, which are somehow related to excitement. In fact the above is the simple definition of tremendous. The full definition, sense 1, actually has something of excitement in it:

1 : being such as may excite trembling or arouse dread, awe, or terror

2 a: notable by reason of extreme size, power, greatness, or excellence < tremendous problems > < a writer of tremendous talent > —often used as a generalized term of approval < had a tremendous time >

Having made my case for tremendously over utter and completely, I’d like to suggest that wildly is even stronger than tremendously as an intensifier for excited. Picking up the Pointer Sisters’ line Benjamin Harman brought to our attention:

"I'm so excited, and I just can't hide it. I'm about to lose control, and I think I like it."

If you say “I’m wildly excited” you don’t even need to explain you’re about to lose control: wild means out of control already. This ngram shows that wildly excited is a more popular choice of words than tremendously excited.