Rental property for sale - but property doesn't show well

[Martin T.]

I have a property for sale in the Bronx in NYC, which has been on the market for 3 months or so.  I've watched other units in the building come on the market and sell, but mine is not.   The price is right, and my agent is getting feedback that it "feels smaller" than ones of the identical floorplan.   Reason being (I believe) is that my tenant has it very unorganized and packed full of stuff.  It's not to the point where it's a hoarder situation, just stuff like an unused treadmill, area rugs everywhere, curtains that aren't hung correctly (no damage to apartment, and it's not unclean, just doesn't present well).  

Another unit in the building shows VERY well (1 floor up, top floor), and sold right away above asking, and mine is priced for less due to it not being a top floor. So it seems like it's the condition of the apartment that prospective buyers can't see past.

I could tell tenant she is free to leave (which she would probably do) then lose about $1,500 per month until it sells.  My agent isn't keen on it being empty, since she feels empty apartments don't show as well either.  I could talk to the tenant about cleaning up (but she's been a bit difficult already with showings).  Have others experienced this and any thoughts?

Thanks in advance!