2d interpolation -- comparison of different methods

Hi,

I'd like to do 2d interpolation on f(x, y) scattered input data (no
order, no regular grid).
The interpolation should go through the original data values.

I'm confused about different methods I found, e.g.

SmoothBivariateSpline, RectBivariateSpline, BivariateSpline, griddata,
interp2, bisplrep / bisplev, Rbf

1. Does anyone have a comparison between these (and maybe more)?

2. Which of these are appropriate to do the interpolation I've written above?

Any help much appreciated.

--
Johannes Zellner <johannes <at> zellner.org>