unfortunately, this is an area that is second only to room acoustic control that people scrimp on. It seems that having a $2000 mic pre is more important than the speakers you're going to being hearing the workings of such a piece through. A lot of budget monitors could sound so much better in a good environment. Sure, the bad parts will be totally exposed but if you know whats wrong, its really easy to fix.
As to your quest.....learn about companies and their products. Here's a few quality monitor companies to check out: Atc, westlake, meyer sound, klein & hummel, genelec, quested, pmc, m & k, tannoy, focal.......all have a certain engineering directive to their product and learning about why they build things the way they do will enhance your engineering ear. Learning about sound transmission is another way to get your chops up.