Hello Redundant Banker, welcome to the Forum!
My recommendation is the 100mm macro lens, as it allows more room for natural lighting and/or flash fill lighting. You will find that some subjects and lighting situations cause the lens to cast a shadow on the work, especially in very-close focusing photos.
Here is an example of a 90mm macro lens with 1:1 adaptor, roughly equal (in view) to the Pentax DFA 100mm which is also 1:1 magnification.
The lighting was weak sunlight from the right and a stronger diffused flash from the left. The silver dial is just under 6mm in diameter, the silver pointer is 6.1mm long and the lettering is 1.8mm high. The mainspring (partly shown) is 18.2mm in diameter and the entire pocketwatch is 47mm in diameter.
The camera was tripod mounted with a cable release and I hand-held the flash at various positions on the left, trying different angles of light. Exposure time was1/2s. The lens is a Vivitar Series 1 90mm f/2.5 macro, also known as the 'Bokina'.
Hope this helps!
Ron