What is your favorite High EFF speaker

Living Voice out of the UK their line is 94db 6 ohm nominal. I push mine with 8wpc granted they probably be better with 20wpc. 

Klipsch heritage line are all very efficient. 

Most of the open baffle design are efficient, Spatial Audio, Pure Audio Project. Eminence. are a few I can think of off the top of my head. 

AudioNote UK AN series are fairly efficient. Require corner placement to sound their best though IMO (former ANE owner). 

Others have give more so i'll stop there. 

glen 

I recently bought a pair of standmount Super6 Alnico Monitors (93db) from Omega Speaker Systems, replacing Vandersteen 2Cis. Driving them with an 18wpc SE KT88 amp from Aric Audio, they deliver a level of detail, liveliness and speed that is simply exceptional. My initial impression was they didn’t deliver very low bass but now that I’ve had them for a couple of weeks and experienced with placement, I now feel their bass is accurately tight and low enough for the acoustic jazz music which I listen to most of the time. Anything else that could deliver this level of detail and speed with quality bass and could also extend down to something around 20Hz would require much larger footprint and cost significantly more. Daedalus speakers could be a great option if they meet your size, decor, and budget requirements.
As a side note, the more efficient speakers, in my case full range single driver, seem to sound a lot better even when you listen to only a single speaker and they seem to maintain that level of detail and aliveness even when you hear them two rooms away.   

Tannoy!

Give the Volti Rival serious consideration.

Not efficient but easy load not huge or bulky and amazingly one of best of show last year off a low watt headphone amp: Fritz Carerra.