That depends on what you're looking for, how experienced you are with MTS and what your own personal preferences, likes and dislikes are in a script. This is obviously indeterminable by anyone here - only you know what's right. In other words, there is no "best" one.
That said, in my own *personal* view, one of the best ones is MTS Loader
by solidsnake - it was the first one I used and had all kinds of features, something I think is good for someone new to MTS.
Hope this helps.