I don't know much about knives but as a hunter of red and sambar I do know my deer. I wouldn't say sambar is any more complex or beautiful than red. It's all a matter of the of the deer, the time of year, where it lives etc. That determine the aesthetics. It's the pearling that really gives antler its beauty in my eyes, that is the textured look it has. If anything I'd say a mature red stag early in the season has far more complexity in its pearling and texture, sambar has more basic prominent ridges running linearly.
They may vary in density and thickness, but all deer antler has pithy parts as antler is bone and needs a blood supply during development. Sambar are typically thicker so probably have more solid bone.
It'd possible that sambar don't rub as much as reds, not sure. But their cast antlers tend to retain their quality, reds on the other hand rub vigorously toward the time of antler drop and late season deer typically have worn off much of their pearling. Farmed reds, forget about it they have very pale antler and wear them down fast rubbing fence posts and such. I think farmed reds would be the main source for antler and probably why any you've seen lacks the eye catchyness.
I've got some hunted red stag heads from early season in my shed that would make incredible knives. There's one 11 pt I shot a few years back that I've been eyeing off for just that.