For me and for a number of email "power users" whom I know, Blackberry strictly dominates iPhone email experience.

Stipulated, it definitely depends on personal preferences and workflows as to what you personally prefer.

But it is pretty incontrovertible that Blackberry was a finely-honed email tool with departures from that core use case being pretty tightly defined around the things you do ancillary to email (setting appointments, reading attachments, etc.).

iPhone is worse at that particular thing -- but vastly more capable broadly speaking for a universe of other things.