Is the most efficient speaker the best speaker?

I purposely kept my question general in order to let let real world considerations bump up against the hypothetical. Of course "all other things being equal" doesn't exist -- except in any one particular system -- but interesting and useful information has resutled. Thanks for all your responses. Carry on.

The most efficient (sensitive) speaker primarily benefits the lowest power amplifiers... is the lowest power amplifier the best amplifier?

If so, then what would be the purpose of manufacturing higher power amplifiers and less than the most sensitive speaker?

Other Things are not the only things that are never equal.

How Dynamic is an 83db sensitive speaker with 50 watts? and how dynamic is a 93db sensitive speaker with 50 watts?
If absolutely everything was identical, the 93db speaker is not more dynamic? Right. Wes, I've heard you make some outstanding well thought out arguments in the past.
Again, the BIG STATEMENT, "All Things Being Equal".
My current speakers are very Dynamic and 86db 4 ohms, but they aren't dynamic with any amp. In the theory above the more sensitive speaker, even when it is only sensitivity that makes the two speakers different, the 93db speaker would be More dynamic without question.

The answer has to be yes, if all other speakers were connected to a 5w tube amp.

"The answer has to be yes, if all other speakers were connected to a 5w tube amp."

No doubt high efficiency is the way to go with a 5 watt tube amp. No arguments there.

However, the most efficient high efficiency speaker still may not be the "best", so the premise as stated still does not work.