I think I need an L lens. Can only get one

The best wide-normal zoom options are the EF-S options. The 10-22, 15-85 and 17-55 will perform at least as well on crop as the L zooms that cover similar ranges and give better range overall.

Teles are altogether different, a 70-200 F4 (with or without IS), 70-300L or 100-400L are all great lenses for crop.