Bottom line, squats will make your legs grow more than the deadlift. The deadlift is recommended over the squat because it is easier to learn--therefore safer.
If you feel confident in your squatting technique, then the squat is better for increasing the mass of your legs. I highly recommend Rob Lawrence's article How and Why I Squat. If you are not familiar with the squat, but are reasonably coordinated expect about a month learning curve to safe proficiency and a lifetime of improving technique.