All system biased aside, I think the ICE MERP products far surpass all others as far as the quality and amount of content.
That's probably, at least in part, because of increasing IP use restrictions and monitoring. Look at what ICE published for MERP during the heydays - a large part of it is completely original content, actually. The games that followed had far less leeway (the shortest leash being on the Lord of the Rings game, which was basically restricted to what the *movies* showed). TOR is a middle of the road kind of thing: there is original content, but it stays within well-defined boundaries.
Things like Shadow in the South, Greater Harad, and Court of Ardor could never be published under a Middle Earth license anymore. What allowed MERP to flourish was the freedom the writers had, even though the line editing was not always up to par (something that has plagued the Shadow World line to a much severe degree before Terry put a stop to it).
