I'm trying to fit it in this weekend. I've ordered a 20l barrel "Mannol 8218" after reading through a few recommendations here and in other forums.
The Mannol seems to be well recommended, I haven't tried it. It's around €50.- here in Germany.
Until now I've always used "Fuchs" ATF, very good, but to expensive for a first flush (I got this car only four months ago). After two or three flushes over the next few months, I'll go back to the Fuchs ATF, as a "year-long" filling.
So depending on how long you try to drive this fluid, choose one. Oh, and before I forget: I've read a tutorial