You asked

Best camera for the leica apo macro elmarit sl 100mm f 2 8?

For this lens, I'd shoot it on a full-frame body. That's what it's made for, so the 100mm reads as marked. On APS-C you get the view of a 150mm, which is a different lens for macro work.

My picks from the list of bodies it fits:

If you're unsure, the Sensor sizes guide explains what full frame costs you in size and price. For the field of view, the Focal length converter shows how the 100mm changes across formats.

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