An E36 328i with M50 manifold is difficult to beat IMO - cheap, pretty reliable, no VANOS to worry about and replacement bits are easy to get hold of
they are also not lacking in power which is always a good thing
C200Ks are like 180bhp, and that through a semi-auto will be wank.
My C230K was manual and a good 50bhp more. That was awesome. Tons better than the usual E36s etc.
W203s look great, but a C200k auto will be a bit gutless. I'd have a bigger engine BM over that from a drift point of view.
i have a clk 230 semi auto as a daily at the moment. and its shit when trying to use the gears.