I used to own the AR-2ax and the AR-5, now owning a pair of AR-4x speakers. The 4x is a very well balanced small speaker and as others have pointed out, fit in a smaller listening space. I thought the 2ax and 5 were power hungry, both went away in 1974 for a pair of JBL L100s (perhaps a mistake).
I recently picked up a nice, minty pair of DLK model 1 last year and they can give the 4x a run for the money.
If I were to get another AR 3-way, it would be the 5.
The AR-4x sold for $57 in my 1969 allied catalog in oiled walnut. The 2ax was $128. The AR-5 was not yet available.