What are the best speakers you have ever owned and why?

My speakers, described above, are essentially vintage/custom speakers that are not commercially available.  An important feature, to me, is that they are extremely efficient so that they work with low-powered amps (the only kind of amps I really like).  High efficiency options in commercially available speakers are somewhat limited.  The Audio Note and Devore speakers, while not extremely efficient, do work quite well with low-powered amps and they sound pretty good.  My favorite commercial speakers come from Charney Audio, but they can only be auditioned in New Jersey (or at audio shows).; the model I heard, and really liked, was reasonably compact, light in weight and very reasonably priced ($17,000) for a high-end product. 

If you go the custom-made route, check out Deja Vu Audio in Tysons Corner Virginia.  They make really good speakers from around $20k to ?? (I heard a million plus system, but, that included custom-built speakers and amp and linestage and phono amp, plus Audio Note DAC and transport and a turntable setup).  Deja Vu custom speakers can also be heard at affiliated Deja Vu stores in Miami and Los Angeles.  Goto makes components for assembling custom systems that sound very good, but, the components are extremely expensive (looking at six figures for just the drivers).

As a former dealer, we had pretty much every good speaker to listen to and compare to each other.  After a couple of years of doing this with various electronics attached, we realized that all box speakers and electrostatic versions had some positive qualities when driven with quality electronics. 

It was not until we hooked up Magnepan products that we finally realized that NO box or HORN or ELECTROSTATIC or RIBBON or any combination of these reproduced sound as accurately as Magnepan products.  Some better than others, of course, and positioning is a key item--and VERY frustrating at times--but at the end of the day, no matter what we put next to them, Magnepans were more accurate.  

Now, you may not LIKE accurate, so they are not for everyone.  For example, if you prefer kick-a__ bass, you need Cerwin-Vega (in those days) or Hartley 24" woofers, etc.  If you LOVE those shrill highs, you will love most electrostatic and/or ribbon models, etc.

This is what we discovered--no bias going in, but sure had some coming out.  Not many people are fortunate enough to have access to 20 or 30 brands of speakers and quality electronics to drive them (we were what was called back then a "HIGH-END" shop) and had only the better items on the shelf.  This is merely the result of our exploration. 

By the way, the boxes that we felt were the "best" back then were Fulton 80's and especially 100's.  Our college-day faves, Advents, were VERY, VERY INACCURATE, and the tweeters blew out at volume. We all learned a lot back then and I maintain that high quality tube electronics and Magnepan speakers can be dialed in to provide the most accurate music reproduction you can find.  Once again, you may not like it, but play your personal favorite instrument live next to a system like this and all will be revealed.

Cheers!

Advent New Large Utility, JBL towers (mid 80's), Vandersteen 1C, to my current and final Ohm Walsh 2000.  Short of winning the lottery, they stay.  They do almost everything right (my review is posted here in review section).  Not the best speaker, but the best I can afford, power, and fit in my room.  I would go for German Physiks if I had the money.  But I am happy every time I fire up my rig with Ohms.

My tannoy vintage hpds are keepers 

In more or less chronological order:- Smaller Advents- Acoustic Research AR 12
- ADS L710 (still have them in BR system)- Infinity RSII- Magnepan MG12 w/ REL sub
- Infinity RSII back again- Infinity IRS Gamma (these were probably the best...only sold them because of reliability concerns)- Gallo Ref 3.1- ML Ethos- ML Montis (I really like these...They can do some things better than the  Gammas)
As you can see, I am very much a panel / dipole person.  Also I have run a few vintage speakers in my BR vintage system, Klipsch Quartet, JBL L100, various other ADS, Infinity RS4.  The ADS L710 have taken on and defeated all challengers.