Listen to Coincident. They are very sensitive, great for tubes.
The best way to judge the speaker is to test your amp with the speakers take your Primaluna Dialogue with you to auditioned some speakers. Thats a nice amp for sure! I love the VSA Vr2 line personally. Many options out there but like I stated before let your ears be the judge and dont purchase something just based on opinions. Most "audiophile" stores will let you borrow their speakers for the weekend to audition. Also, not only the speakers but speaker cables, interconnects, power cord and some minor tweaks here and there, everything has to blend in. Doesnt make sense to have a good Tube Integrated amp with cheap lower quality cables, speakers etc!
"Best speakers for the Primaluna Dialogue" well, thats subjective. Do your homework! Good luck and happy listening!
In addition to all the nice speakers mentioned above and the many out there, my 2 cents ...
I currently have the Primaluna Prologue 2 paired with Aurum Cantus V3Ms and one of the new REL R-series subs, the R305. I never, never get tired of hearing it. The ribbon tweater of the V3Ms is super quick and very lifelike.
To my ears, this is an absolutely heavenly pairing and will fare well with your musical tastes. Best thing is that, given your budget, you'll have change left over for some nice cabling and/or interconnects.
Have fun with your speaker search.
Try the speakers with your amp before buying, if possible at your home. I have use prologue series with Monitor Audio GR20, they were good match. The output level variation wrt imepedance of spakers make these tube amps very choosy regarding speakers. The low damping factor of the amp also makes life difficult for some speakers that go deeper in LF.