Anyway, you need to look at the context.
What is Dae doing? He has an arm that belongs to a being that easily surpasses the Abyssal Ones.
The logical conclusion is that only a number one (since they are the strongest warriors) awakening would produce such a being.
So he's looking for a former number one that might have awakened without them knowing or hearing about it.
Now. In come the original three. Dae is using them as a measuring stick, what with them being the most powerful beings around.
More specifically though, he's looking for any number one who could have surpassed them.
What does that mean? That Dae thought that warriors of Riful, Luciela or Isley's strength probably couldn't awaken into something beyond an AO. After all the three are similar in strength, and, surprise surprise, they awakened into beings of similar power.
Therefore he wants a stronger warrior. Now, tell me, why would he ask that if those three were already among the most powerful (as you're claiming) to exist?
If those three were on par with the other eight (and Dae would know, since it is his area), he'd know no other warrior could be more powerful, and thus wouldn't ask.
In fact, him asking that in itself means he didn't think the three were among the strongest.
Does that mean they were weak? No. I think there is a certain level of raw power you need to have (contrary to what you're saying) to belong in a number one class (which you don't believe in ).
Thus Miata being called number one material, even though she can't be one right now, or Miria and Clare being considered number one materials by most people here.
Remember Rafaela asking Chibi Teresa whether she had a sister? She had just met her, and yet she realized immediately that Teresa had the potential to become number one.
And it's understandable that there will be variations within that class, after all they can't all be the same strength. For instance Roxanne was number two when Cassandra was still alive, despite her herself being worthy of the top position.
And when you're in that class, you become an Abyssal One when you awaken. You don't need to be 'strong' to receive that title. And the thing is, prior to the three Zombies, only three number ones had awakened (unless it's implied somewhere that it's not the case?). That's just too small a sample to assume that the Org gives that title to the 'strong' ones.
Look at Rosemary, who a lot of people seem to think was a weak number one, or just a number two (I don't know why). Orsay urges Teresa to get there before it's too late. The implication being that it would be a catastrophe if she awakened, since they would have a fourth AO on their hands. Even if she was a weak number one, the Org still thought she'd become an AO.
Anyway, back to the MIB. When he answered Dae's question, he chose to ignore his requirement. Namely, that the warriors named be stronger than the original three. Remember that. It therefore has no bearing on what he says after that.
He names those eight not in comparison specifically to Riful, Luciela or Isley. Remember he ignored that criterion. He names them in comparison to all the number ones that existed ('we can give names to no end').
I don't think that just because you're strongest at the moment guarantees you that title. The MIB don't just randomly promote. They seem to put some value in those positions, going as far as to demote warriors as punishment, as Goral noted.
And it's clear the warriors take pride (some of them at least) in their positions. They feel they deserve a certain position because that's what their strength reflects. That in itself would indicate that there's at least a rough idea of what strength each position corresponds to.