I can't speak for the 400/800 considering I've never played on them, but I do enjoy quite a few arcade conversions on the 2600. Berzerk is excellent, and Millipede has proven to be every bit as addicting as it's arcade counterpart. With the VCS, there is quite a bit of strategy involved, as you often have a much smaller playfield and therefore have to adjust accordingly. I guess that's just one of the things that makes playing on the 2600 such a unique experience.