#lorica segmentata

Common mistake here, the Romans did have chain mail, the lorica hamata. Best and better are subjective, so it depends on what you look at. Putting on segmentata didn't protect the legs as well since it only went to the waist/hips, but the points where it did protect were better. Segmentata was harder to deal with in terms of putting it on or repairing it (all those brass fittings), but it was lighter, 8 kilos over ~11 kilos, which anyone whose been on a ruck can tell you is very welcome. Hamata was labor-intensive, but less complex to make and wasn't as necessary to be customized for the user's build and girth which would make it more common and cheaper, mundane reasons to explain why hamata was more ubiquitous even during the height of Rome. Trajan's Column is pretty awesome, but just as I mentioned about my answer on the falx, was an idealized depiction.

Then you have to note that the pieces themselves are not standard, even during the days of the fabrica. So it really is a matter of circumstances, advantages, and trade-offs. I believe most legionnaires would probably want segmentata due to it's better protection on the torso, and cover the hip-knee region with a good shield, but I'd certainly be annoyed if my fittings were damaged and repairing my armor on expedition became difficult and costly.

Thanks for the question, Anon.

Detail of Arch of Constantine: Detail of relief panel, south side, right panel of left arch. A legionar wearing lorica segmentata.

The "Indomitable Trooper" Blood Legion Standard Armor.