what speakers to buy??

Strange question.

Any you like that your amp will drive.

Karim...you may want to narrow your question a bit by describing what sonic qualities in a speaker you are looking for, or describing th etype of music you like to listen to, as well as give Agoners some sense of what budget you are working with, and how large your listening room is. This will help tailor the suggestions to your specific needs (well theoretically that is). Good luck.

Yes, you definitely need to say what you are looking for sound wise, size of speaker, room size, and there's probably more. Here is the specs in this link for the Op's 250 watt per channel amp.
[http://www.mcintoshlabs.com/us/Products/pages/ProductDetails.aspx?CatId=Amplifiers&ProductId=MC252]

Vandersteens have always been a greaqt match for Mac amps.

thanks for the suggestions. the space is a loft, so that doest really help, but let's say the spacial range is within the 12 to 15 foot distance, the ceilings are 20 feet tall. The music range is vaste, not strictly jazz or classical. The budget would be from 4 to 6k. thanks guys.