ADS, EPI, Polk (many like the model 7), some of the Norman Labs (I have the model 8), etc, etc, etc. It all depends on what your ears like.
Scan CL on a regular basis. Go to garage sales, thrift stores and estate sales (if you have the time). If you see speakers advertised somewhere, go listen to them.
I recently picked up a small pair of DCM's at a thrift store (cheap) that play very nice with the Normans. If something's cheap enough, you take a chance. Sometimes you get lucky.
I would not buy used speakers online unless I had listened to that make/model before and knew what it sounded like. I've bought new, online, (due to rave reviews) that I sent back because my ears didn't like them.
I looked at a small set of older Polk's today because I wanted the Peerless tweeters for another set of Polk's that I have. I listened to the tweeters, using a paper towel tube, and one of them was not working. Glad I checked them out before buying.