Canon uses the red L badge to designate more expensive lenses (L stands for luxury). By definition, none of the lenses designed for crop sensors carry the L badge and the L does not necessarily imply superior image quality. For instance, the
85 mm f/1.8 non-L bests its big brother, the
faster f/1.2 L, in terms of image quality. The previous-generation 100 mm macro did not have an L badge, but it is a very, very good lens.
Since Canon will not give crop lenses an L badge, there is a tendency to look down on very capable lenses whose focal length is a much better fit (e. g. Canon's 17-55 mm f/2.8 comes to mind), and what you should first decide on is a
focal length and not a marketing badge.* Also, none of the third-party lenses carry the
L (obviously), even though some of the third-party lenses are very good -- especially when it comes to price/performance. For instance, my always on lens is a 30 mm f/1.4 Sigma prime lens. The equivalent Nikon lens (I own a D7000) costs more than 4 times as much! Also Tokina makes very good lenses with a solid construction.