Best Speaker for a reflective room ?

It’s a rather large room.  Perhaps you can have a relatively near field system using omnis planted near the center of the room.  

Stiffle finish painting on walls. Furnishings, paintings on walls with or without absorption foam hinden. False ceiling there are many options. An acoustic consultant or your reasearch will open many vistas.

I agree with kota1. Black Ice audio preamp and choose a speaker with attributes you like. Call and ask for Jerred at Black Ice audio. Great company to deal with.

@peter_s I agree.  With such a large room, try to arrange some furniture so that you have a smaller listening area where you sit closer to the speakers and have an open space behind your listening position.  

I have a long deep room (14 x 42) with one side about 40 feet of glass, and the other side opening onto a hallway and kitchen with no doors to close.  Large Ohm Walsh pretty much in the corners fill the space with dense, crisp sound.