Hello Steven,
as everyone knows, nothing is without a past. Before 5.1 there was 4.0, aka quad, and the past is open for today's learners.
Other than "personal tastes", which "old quad" mixes did you found intresting as a learning experience on how to mix, placements, moving elements, balancing etc? Something that, when you were listening it, you were thinking "wow, that's great, this really does add a depth in the musical artistic experience, how they did it...".
I'm sure at least 99% of the people here will list PF DSOTM on a personal top5 - Alan Parsons has been a real genius on that. Your top5 "old school quad" mixes?
Thanks.