in the $50 range, the atac alium is clearly superior to the eggbeater c in terms of durability
the more expensive eggbeater sl and the atac xs both enjoy popularity.

atacs are preferred by some, including myself, because of the positive click engagement, the bearing quality, the adjustable release tension on higher end models, the resistance at the end of the float, the cleat durability, and the larger platform, which is reputed to be more comfortable on longer rides.