Speaker choice

If you can locate the speakers out in the room 3ft or more from the back wall, a 2X8" 3-way tower would work. If you have to place them closer to the rear walls, id consider a 2X6" 3-way design. I prefer dual ports for tunability via port-plugs, and rear mounting for most efficient room loading, although bottom mounted ports on an elevated plinth can work very well. Within those parameters there a lot of choices. I'd avoid anything over 10 years old or from out-of-business manufacturers simply for serviceability reasons. In your price range and to my ears, Monitor Audio, KEF, Sonus Faber, and Revel all make exceptional products, with nods to Golden Ear and Sourcepoint for their unique takes. All of these represent great values as well. And of course everyone should own a pair of Magnepans at some point, provided you have the requisite 100W/ch high current amp and a Maggie-friendly room. 

Finally comes your specific tastes, both in sound quality and esthetics, not to mention SAF. So you really have to listen to as many as you can, do  your research, and know what matters most to you. For me, image and soundstage, dynamics, bass control are all critical, but if the speaker has all those and makes human voice muddy, boomy, honky, or nasal, dead stop, nope. 

Most importantly, enjoy the process. And when you finally decide, enjoy the music.

Hello OP,

All the above suggestions are great. IMO, if you like the sound of Harbeth speakers, you might just want to stay with their bigger models (house sound) rather than moving to other brands. Just get a bigger model but used to keep cost down

But if you wish to move into other brands, highly suggest that you audition it first. Based on what you wrote, the size of the listening area is similar to what I have, (13 x 23 for me). Although I listen near field, I still believe that stand mounts can perform well. My speakers are Ls3/5a and ATC and they can perform well (loud enough) in my listening area (80 to 90 db.). For me, the perception of the big "you are there" sound is driven by Subwoofers, that your Harbeth needed. In my case, I use 2x Rel T/7x Subs, integrated (using ROON) well in my LS3/5a. AND, I Use a good amount of Room Treatment. All this creates a Synergy that makes my small speakers sound loud enough, as long as you listen near field.

If you wish to move to other brands, I have heard the MoFi Sourcepoints which sounds great and i believe as others have said above, the Tekton models ( i have not heard them)

@starystarynite  But I couldn’t feel the speaker is not enough as the space is too huge for it. Now I have sold my speakers...

 

Not enough of what?  

In my experience for the cost of two mid-priced off shore made 'Sub-Bass' speakers a distributed bass array Swarm would have loaded your unusual room with a clearly better integrated mid to low frequency presentation, adjustable to the speakers you just sold or any future speaker choice.   

Mobile Fidelity Sourcepoint 8. Andrew Jones design.  Under 3K new with stands. Buy from Crutchfield and try them. If you don’t like, return and get full refund. Nothing to lose. If you want to spend more money and want bigger sound, try the Model 10.  4K including stands.  May not need sub. Could do alot worse for the dollar.

@starystarynite 

Check out Spendor A7.  Spendor delivers the dynamics of horn speakers with the refinement of box speakers and a huge, well defined sound stage.  Like listening to a fireworks display or kaleidescope.  Very enjoyable speakers.