The Vertex 4 will probably be a little faster (although maybe not, once it is filled to 50% or 75% capacity), but I doubt the difference in speed would be noticeable except if you run benchmarks. The Samsung may be a tad slower, but its speed is consistent and predictable. The V4 performance tends to vary.
The Samsung 830 has almost a year of history now, proving itself to have no major design flaws, no serious hardware incompatibilities, and no pattern of failures reported by owners. The V4 has a few months of history with frequent, major firmware updates, most of them destructive. Also, Samsung has a much better history of quality products than does OCZ.
I think the Samsung 830 is the clear choice. Although I'd also consider a Plextor M3 or M5 if you can find one for about the same price.