Is a GIA diamond report better than others? What are the differences between the reports?

I noticed there are different types of diamond reports, i.e. EGL, HRD. Are any of them more reliable than others? What are the differences? I'm going to buy a loose diamond online so I'm trying to be cautious.|||Yes! GIA and AGS are your best bets for a reliable, accurate report.. EGL, HRD, all those others are diamond dealers first, so there is a tendency to inflate color and clarity grades to drive the prices higher...|||what Randi L said is true however EGL is also cheaper so for smaller diamonds a dealer is more likely to go to them