For me personaly i allways use Securebob it's a good Speed/Quality tradeof for me.
but the best Speed/Quality @ the moment wich sadly yet can't be used (at least no one wrote a custom allocator for it yet) is Nvidias Per Pixel Adaptive Motion Deinterlacer inside their Mpeg-2 Decoder (PureVideo) it has no problems to convert 1080i into double framerate progressive Video in Realtime (on the GPU) pretty exciting to see that in front of your eyes, quality isn't as good as tdeint tough
Tdeint with GPU support that would be the revolution