FD lenses will be optimized for 35mm cameras, which makes them ideal for adapted use on a full frame (FX) camera.
Arguably, there is another "sweet spot" when using them on an APS-C (DX) camera, because you will then only get the very best of the juicy center of the image circle.
Do be aware that a 24MP APS-C sensor is extremely demanding of lens ...
So - which system is best for use with FD lenses?
Neither EF nor MFT are ideal for adapting FD lenses.
To adapt FD to EF requires corrective optics with a 1.4x multiplier.
MFT has a 2x crop factor. With a 0.72x focal reducer, this can be converted to 1.44x.
If you intend to use adapted lenses extensively, consider an APS-C or full-frame mirrorless camera. ...
I see the FD to MFT adaptor doubles the focal length, so does that mean it’s not worth it? None of my lenses would be particularly wide any more.
So, uh... buy a wide angle lens or two to complement your existing lenses?
On the other hand, I’m having difficulty finding resources for using FD lenses with an EF mount - surely if there’s a full frame ...