As much as it is rare, LAPC-I can only be used in a system with the ISA slot. And then there's the issue of the -5v requirement in the PSU for it to work properly. But that does not decrease the desirability of a true Dos gamer to own one even one bit. But practicality takes the precedence.
The modules too require true MPU-401 intelligent mode capable interface card in old systems for proper LA synth message transmission. (Soft MPU is trying to fix this issue with non-intelligent MIDI interfaces.)
The main advantage of the modules is that they still can be used with modern systems, via the USB-MIDI cable and Dosbox. And you can attach the module to any of your systems. (Without the need for the ISA interface card).
I would choose CM-32L and the SC-55. Covers almost any Dos game with "luxury" MIDI requirement.
If I can only choose one, I would go for the CM-500.
I would also change the rules to include 3 - The MT-32 - mainly for the MIDI message. It's nice to see the messages when certain games are being played. And the first gen ones are ideal for the earlier games designed for the MT-32.
If the rules can't be changed, I will stick to my selection - mainly for the additional effects on the CM-32L.
But...but...the original MT-32 is so tempting......with the nice LCD display with cute messages by the game designers (like Sierra)...