I've played several games now that share ports on the 3DO, Saturn, and PSX. When it comes to 3D games, generally the PS1 has slightly better resolution graphics than the saturn, while both keep up the same framerate. However, the Saturn 6-button controller is far superior to the Playstation controller, so the "gameplay" as a result of the controller is so far always superior on the Saturn version.
On a few games, the playstation developers went out of their way to show the best visuals, and the frame rate actually suffered a bit as a result. So a few times I've ended up with a game that had crisper higher res textures and better colors on the PS1, but had a much smoother frame rate on the Saturn. In the end, I've always ended up choosing the better 6-button controller/gameplay over the slightly enhanced visuals.
The 3DO always lags in both resolution/color and frame rate to the Saturn and Playstation. And the fact that the 3DO controller D-Pad is quite poor make it almost always lose. I usually stick to 3DO exclusives on the 3DO.
However, some 3DO originals that were later ported to Saturn/PSX tend to still be better on the 3DO, just because they were originally developed for the system, like Gex. Another one is Road Rash, which even though it suffers in frame rate compared to the Playstation version, the Playstation controller is so horrible that the 3DO actually plays 1% better.