OK I guess I'll throw in my opinion again (though I rather someone just created a Legion vs NCR thread instead because there's more to that debate than this one
). Anyways, I'd like to think I'm not biased as many clearly are on here but here goes..
We have to look at what we're given to be lore. Gameplay stuff just doesn't matter in a debate like this so all of the "Ranger vs Centurions!!" video you can post doesn't change anything.
What are the pieces of lore we're given in NV?-Firstly Chief Hanlon explains that the Centurions were the best of the best of the Legion, having killed hundreds of men to qualify for their rank. That Centurions don't have an equivalent in the NCR army. (you'll see this thrown out a lot)
-We're led to believe that the Ranger Veterans are the best the NCR have to offer as well: only the best of the army are chosen to apply, of those who apply to be Rangers about 80% do not make it out of training (forgot who says this. Maybe Andy? Either way it's on the wiki).
What are the known interactions between Rangers and Centurions that we're given in NV?-The First Battle of Hoover Dam: After the CL took the Dam the NCR fell back and the Rangers were put on a ridge. By all accounts the rangers completely devastated the Legion officers and elite soldiers during Graham's 2nd (and last) assault during the battle
-Silus' men were defeated and the Centurion was taken prisoner. We don't have much information of the battle except that it was clear that the NCR won and won big because many of Silus' men resorted to suicide before being taken captive
-Stella, the ranger captive at the Fort's arena. Otho claims that rangers are very rarely taken alive (something that can obviously be said about Centurions as well). She has apparently killed many legionaries and even a Centurion in the arena with her bare hands. Though the Devs did buff her ability in the game this is irrelevant: we are not discussing gameplay here. It is lore now that a ranger killed these men in the ring. When you defeat her Otho responds by saying something like "Unbelievable. Someone could defeat a ranger in single combat." This is pretty damn telling imo.
Their armorThis is pretty irrelevant to be honest but a lot of people seem to care so whatever... Centurions have better armor. Deal with it. The ranger vets are wearing [censored] jeans for crying out loud. Moving on.
My conclusionMerely based on the dialogue we're given in NV, and we are indeed given very little (here's to hoping for more in the future),
I'd have to give it to the Rangers. Centurions are without a doubt a force to be reckoned with but the rangers just seem to have a better track record against them. Simply making an argument around one line one NPC says about the Centurions and how badass they are just doesn't hold up to the fact we know and see in lore rangers dealing with Centurions.
Again, we aren't given much information so here's to hoping for more and maybe some day we'll see behind Legion lines.