If you can afford it, then SMS is the way to go. Crimp roofing relies on screws through the metal. SMS has clips tucked in underneath and then rolled into the seam. It's also installed with the edges around the fascia folded onto the drip edge which provides for additional holding power. You'll often see crimped roofing on older buildings torn up at the bottom corners and sides after strong winds.

Benefits of 5V Crimp:

1. Price (Unpainted, about $.75 a running foot cheaper)

Benefits of Standing Seam:

1. Heavier gauge steel than 5V Crimp. Thicker steel = more durability and wind resistance.
2. Better paint performance: our standing seam comes with a 40-year paint warranty.
3. Installed with hidden fasteners: Like Solar Texas said, 5V crimp gets filled with screw holes that can be a source for leaks. Our standing seam is screwed at the ridge (which is fine since it is covered by the ridge cap), and held in place along the sides by clips that get covered by the next panel. So you end up with a completely weatherproof roof system.

We (A.B. Martin) still get requests for both. But from my experience, 5V Crimp costs more in the long run. You can see our metal panels here: http://www.abmartin.net/metal-roofing-panels

And if you want some ideas, check out our photo gallery: http://www.abmartin.net/post-frame-buildings/photo-gallery

Both comments above are spot on. I'd add a coastal-wind and hail perspective since we install metal roofs in South Carolina:

On wind: the fasteners are only half the story. Standing seam panels are held by concealed clips that allow thermal movement while resisting uplift — most systems test to 140+ mph, and some meet Miami-Dade standards. 5V crimp relies on thousands of exposed screws; as washers age and screws back out (especially in heat cycling), uplift resistance drops noticeably. In storm country, insurance carriers increasingly differentiate: a 5V roof often doesn't get the same wind-mitigation credits that standing seam can.

On hail: thicker gauge helps, but honestly both will show cosmetic dimpling from large hail. The difference is what happens after. Hail that dimples a standing seam roof rarely breaches it — no exposed penetrations to compromise. A hailstorm that dents 5V crimp can also loosen the screws sitting in the dented spots, which is when leaks start.

One practical tip: if budget pushes you toward 5V, insist on 26-gauge minimum (not 29) and a reputable paint system (Kynar 500 / PVDF). That closes a lot of the longevity gap for a fraction of the cost difference.

— Roof Repair Florence (licensed roofing contractor, Florence SC)

Depending the architectural style of the building, a corrugated metal roof can be charming and cost effective.