Best speaker for vocals

Forgot to ask room size and listening preference;near field or moved back.

Room size is 15 x 18 with vaulted ceilings, i am using a Juicy Music Peach II preamp and B&K 200.2 amp. I sit about 10-12 feet back and the RF-7s are about 8 feet apart. Overall the sound is very good but I am always looking for improvements and I think the speakers would be the next logical move.

What are opinions on a speaker that is known for its midrange?

Quad esl 57
Harbeth
ATC

are all well known for midrange quality.

I want the most realistic vocals. I have read that Harbeth Super HL5 may be the ticket but it is not full range and there is no matching center.

The large Quad's are hardly practical for HT and lack the dynamics so IMHO you should definitely check out ATC. Many of the movies that you buy (Hollywood productions) will have been done on ATC's anyway. The ATC midrange is roughly 30 years old but it is still in demand by clients in world class new facilities. The fact they buy a thirty-something year-old midrange design speaks volumes.

I would add that "best" is still very much a matter of taste and some like ATC and some don't. So make sure you audition.

The new Klipsch Palladium p37F look very interesting

Maybe merlin's monitors or floor standers could fit your requirements;excellant speakers.
Also a used pair of dunlavy scIII's,IV's, or V's might work.
Last what about a different amp;like a moscode hr401 (hybrid)?