Hello Rein:
The thing is "neutral" is not an easy word to say beacuse hipanic people is going to go crazy. It is like if you ask for the most "european" country in europe...
Jokes aside, in my opinion your question have two answers:
Are you learning spanish from Spain?, then you already know the answer. Many foreing people will prefer to learn spanish accent because they`re gonna stay there for a while or maybe forever, or they just like it.
In Latin America it is the colombian's the most paused and also formal and after them, I think it is the people in Lima - Peru (it is more flat, not many entonations, also paused), the venezuelans (paused and sounds good), and some mexicans (Just a few!). Any other latin american country will speak faster and/or will use more colloquialisms.
Another facts:
We, the latin americans don't like spanish people accent and neither they like ours. This happens with the movies, when they are released for theathers most of the translations (audio re-recordings) are made for spanish people, the latin americans, and sometimes also for the argentinians
Sorry for the mistakes in my writing, and I hope I helped you.
Greetings!