You would probably get more improvement by treating the room instead of new speakers.
Best floorstanding speakers under $2000
I currently have a pair of Axiom M60s, but am starting to feel the upgrade bug. I'm looking for another floorstander for rock that is under $2000 new or used and extends below 30hz. I would prefer 8" drivers if possible, but this isn't crucial as long as they go to 30hz or lower. I'm appreciate any suggestions to get my shortlist started. Thanks