What to buy?


Hi: I'm looking for a good pair of floor standing speakers but I don't know anything and I'm hoping for suggestions here.  I've been considering Martin Logan Electromotion, Goldenear Triton 3+ and Revel F35. I can raise about $2,000 in a month. The room is 20 x 20, the music is mostly rock. The amp is an Emotiva XPR5 which has respectable power. I don't mind something good that's maybe been superseded, trailing edge, a floor model or demo - but something you can't argue with at the price.

Thanks - rev
revnice
Save a little longer and get Klipsch Cornwalls. Add subwoofers down the line and you'll easily hit 115 dB and have the remarkable detail and dispersion of horns. For medium powered amplifiers there is no better speaker for a rock and roller. 
If you aren't the tweaky audiophile type who values space and imaging above all you might look at Klipsch.  They are really fun speakers and can dig out something good with even the junkiest of recordings.  I have the Forte III and in many ways enjoy them just as much as my Kef Blade 2

I’ve listen to the LS 50 and R500 and for the Classical music I listen to, there is
a significant jump up with R500 .

Somehow, you need to change the dimensions of your room. Having a square room, you’re already starting wrong from the gate.
Because of the high sensitivity of the Klipsch  Cornwalls ( 102dB @ 2.83V / 1m ) and Klipsch Forte III (99dB @ 2.83V / 1m), I usually associate them with lower power amplifiers primarily of the tube variety.  Since the OP  Emotiva XPR5 is 400wpc, I wonder how well efficient speakers perform with above average powered amps.