The one which (a) has all the facilities you require and (b) you feel most comfortable working with and (c) works reliably.
It really is a case to some degree of horses for courses (ie Mac or PC, matching your technical requirements and matching your budget) and then of personal preference.
Most of the better packages come with a 30 day trial. The Vegas trials are 30 day unlimited. The Adobe Premiere trials IIRC publish a watermark.
30 days is either plenty long enough or nowhere near long enough to get to know the product well enough depending on your perspective. (I've been using Vegas for three years and still feel I've only scraped the surface)