Human Paragon is probably better, but it doesn't have the option of early entry to skill-gated PrCs. From what you've provided, it seems that Master Sensei's early entry is effectively trading 3 base class levels for 1 PrC level (2 levels of Master Sensei plus the level that you use to prematurely take the PrC), which is an iffy trade in most cases, but could be worthwhile for the right PrC. Anything with accelerated casting, such as the Sublime Chord, would get even kookier yet another level early.