Fastest is the gl2n64 plugin but it will only work on some games. (MK64)
Second is the rice plugin which work on most games but it has some slowdowns in some games which I believe is due to the texture handling (see SSB yoshi map).
Third is GlideN64 which essentially only run well with VGA resolution 640×480 or possibly up to 800×600 and is one of the most accurate plugins with very few glitches.
Last but not least you really need a Pi2 overclocked to CPU/1GHz SDRAM/483MHz and GPU/500Mhz to get a reasonably smooth experience on most games.