AR-15... Much more versitile...
The M-96, OTOH, is a fine example of a good idea never quite finished...
It's supposedly based on the Stoner 63, a system (and it was) designed by the same guy who did the AR, with the intention of creating a 'universal' rifle that could swap between a DMR-type weapon, an assault rifle, or a beltfed LMG just by exchanging parts... Completely modular (moreso than the AR), you could even move the magwell around from top to bottom as needed...
The problem is that Robinson Arms only did the parts for the assault-rfile part of the system. If they had actually made a complete Stoner-63 semiauto clone (with optional belt feed and DMR barrel modules), it would be perfect...
But they didn't, and the AR is still the most modular gun available today... Get one...