the first edition of the Edge/ Lo-Pro Edge bridges were the standard to beat, they work fine, they still do & you note pro players like Vai & Satch still have these in their guitars till today. the Edge Zero were necessary modified version to address some patent issues (as with other Edge variants by Ibanez), do note that the EZ models reverted to the knife edge pivot design which is the highlight of the Edge performence.
so which one for you? if either model appeals to you, by all means, embrace them. i own all the Edge versions & i must say that there's nothing averse with original version, it's still the standard to beat.